2. ccnp route qa eigrp
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CCNP Route 642-902 Questions/Answers - EIGRP
2013 1
Refer to the exhibit. Router RTA is the hub router for routers RTB and RTC. The Frame Relay network is
configured with EIGRP, and the entire network is in autonomous system 1. However, router RTB and
RTC are not receiving each other's routes. What is the solution?
A. Configure the auto-summary command under router eigrp 1 on router RTA.
B. Issue the no ip split-horizon command on router RTA.
C. Configure subinterfaces on the spoke routers and assign different IP address subnets for each
subinterface.
D. Check and change the access lists on router RTA.
E. Issue the no ip split-horizon eigrp 1 command on router RTA.
F. Configure a distribute-list on router RTA that allows it to advertise all routes to the spoke routers.
Answer: E
Split horizon controls the sending of EIGRP update and query packets. When split horizon is enabled on
an interface, these packets are not sent for destinations for which this interface is the next hop. This
reduces the possibility of routing loops. By default, split horizon is enabled on all interfaces.
Split horizon blocks route information from being advertised by a router out of any interface from which
that information originated. This behavior usually optimizes communications among multiple routing
devices, particularly when links are broken. However, with non-broadcast networks (such as Frame Relay
CCNP Route 642-902 Questions/Answers - EIGRP
2013 2
and SMDS), situations can arise for which this behavior is less than ideal. For these situations, you may
want to disable split horizon. In this example, routes received by RTB and RTC are not being sent back
out the same serial interface on RTA, so they are not receiving each other's routes. Disabling Split
horizons on interface S0/0 on RTA will fix this issue.
A router has two paths to reach another network in a different autonomous system. Neither route was
generated by the local router and both routes have the same default weight and local preference values.
More on: Link1
CCNP Route 642-902 Questions/Answers - EIGRP
2013 3
When troubleshooting an EIGRP connectivity problem, you notice that two connected EIGRP routers are
not becoming EIGRP neighbors. A ping between the two routers was successful.
What is the next thing that should be checked?
A. Verify that the EIGRP hello and hold timers match exactly.
B. Verify that EIGRP broadcast packets are not being dropped between the two routers with the show ip
eigrp peer command.
C. Verify that EIGRP broadcast packets are not being dropped between the two routers with the show ip
eigrp traffic command.
D. Verify that EIGRP is enabled for the appropriate networks on the local and neighboring router.
Answer: D
Two EIGRP routers can become neighboring even hello and hold time values do not match.
The point of this question is about the condition of establish EIGRP neighbor. You can use these ways to
troubleshoot the EIGRP connectivity problem.
1. Whether EIGRP is enabled for the proper networks.
2. Whether the K values of EIGRP neighbors is the same.
3. Whether EIGRP autonomous number is the same.
More on: Link1
CCNP Route 642-902 Questions/Answers - EIGRP
2013 4
Refer to the exhibit. You are the network administrator in your company. You have been tasked to
implement a hub and spoke EIGRP topology over Frame Relay to provide connectivity between the
networks at headquarters and all 300 spokes. Before you begin the actual implementation, which three
pieces of information are more important to know than the others? (Choose three.)
A. The Committed Information Rate of all the Frame Relay PVCs.
B. The Cisco IOS version running on all the routers.
C. The router model number of all the spoke routers.
D. The number of HQ networks connected behind the headquarter routers.
E. The routing policy, such as whether or not the spokes can be used as backup transient point between
the two headquarters routers.
Answer: A, B, E
- When configuring multipoint interfaces (especially for Frame Relay), bandwidth is shared equally by all
neighbors. EIGRP uses bandwidth command on the physical interface divided by the number of Frame
Relay neighbors connected on that physical interface to get the bandwidth attributed to each neighbor.
EIGRP configuration should reflect the corresponding percentage of the actual available bandwidth on the
line. When configuring multipoint interfaces configure the bandwidth to represent the minimum CIR
times the number of circuits.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 5
If the topology has a small number of very low-speed circuits, these interfaces are typically defined as
point-to-point so that their bandwidth can be set to match provisioned CIR.
- Hub and spoke topologies commonly use stub routing. In this topology, the remote router forwards all
traffic that is not local to a hub router, so the remote router does not need to retain a complete routing
table. Generally, the hub router needs to send only a default route to the remote routers. The EIGRP stub
feature was first introduced in Cisco IOS Release 12.0(7)T.
- Limiting the scope of query propagation through the network (the query range), also known as query
scoping, helps reduce incidences of SIA. Keeping the query packets close to the source reduces the
chance that an isolated failure in another part of the network will restrict the convergence (query/reply)
process. Remote routers rarely need to know all the routes advertised in an entire network. Therefore, it is
the network manager’s responsibility to look at what information is necessary to properly route user
traffic and to consider the use of a default route.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 6
Refer to the exhibit. The Route.com company is running EIGRP between all the routers. Currently, if one
of the LAN links (LAN1 or LAN2) at the headquarters flaps (goes up and down), the HQ-RTR1 and HQ-
RTR2 routers will experience high CPU usage and have a long EIGRP convergence time. As the new
network administrator, you are asked to investigate this situation and determine if there is a quick way to
resolve this issue. Which is the most important thing that you can quickly verify first to resolve this issue?
A. Verify that the bandwidth setting on all WAN links is correct.
B. Verify that the HQ-RTR1 and HQ-RTR2 routers are configured to send only a default route to all the
spoke routers.
C. Verify that the HQ-RTR1 and HQ-RTR2 routers are configured for EIGRP Nonstop Forwarding.
D. Verify that all the spoke routers are configured for autosummarization.
E. Verify that all the spoke routers are configured as EIGRP stub.
Answer: E
Limiting the scope of query propagation through the network (the query range), also known as query
scoping, helps reduce incidences of SIA (Stuck-in-Active). Keeping the query packets close to the source
reduces the chance that an isolated failure in another part of the network will restrict the convergence
(query/reply) process.
In our case spoke routers will be configured as stub with commands:
CCNP Route 642-902 Questions/Answers - EIGRP
2013 7
Spoke(congfig)#router eigrp 1
Spoke(config)#eigrp stub
, if we use EIGRP AS 1.
In this case because we have failure on one of the LAN links, queries for this network will not be sent to
spoke routers. Configuring spoke routers as stub we are reducing the bandwidth overloading and chance
routes to become SIA.
Note: There is another method for limiting the scope of query propagation through the network (the query
range) for our scenario. That is using route-summarization. If we configure route summarization on HQ-
RTR1 and HQ-RTR2 routers with command:
HQ-RTR(config-if)#ip summary-address eigrp ip_address_of_LAN netmask_for_LAN
on their outbound interfaces towards spoke routers, then summary route for LAN will be advertised.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 8
Refer to the exhibit. When you examine the routing table of R1 and R4, you are not able to see the R1
Ethernet subnet on the R4 routing table. You are also not able to see the R4 Ethernet subnet on the R1
routing table. Which configuration change should be made to resolve this issue? Select the routers where
the configuration change will be required, and select the required EIGRP configuration command(s).
(Choose two.)
A. R1 and R4
B. R2 and R3
C. ip summary-address eigrp 1 10.1.1.0 255.255.255.0
and ip summary-address eigrp 11 10.1.2.0 255.255.255.0
D. variance 2
E. eigrp stub connected
F. no auto-summary
Answer: B, F
Problem with auto summary comes when we have discontigious network, as in our example from R2 and
R3 perspective.
Because auto-summary is enabled by default, router will put in routing table routes to its networks first
and will make summarized routes to classful boundaries 10.0.0.0/8. Here it had to be two different
destination routes to the same 10.0.0.0/8 network, which can cause traffic to be sent to the different
router. Router IOS isn’t going to permit this.
To avoid this scenario we have to issue no auto-summary command on R2 and R3 and all connected
networks to R2 and R3 will be advertised.
More on: Link1; Link2
CCNP Route 642-902 Questions/Answers - EIGRP
2013 9
Refer to the exhibit. The actual speed of the serial links between R2 and R3 are 256 kb/s and 512 kb/s
respectively. When configuring EIGRP on routers R2 and R3, the network administrator configured the
bandwidth of both serial interfaces to 512 kb/s.What will be the effect?
A. EIGRP will overutilize the 512 kb/s link.
B. The interface "delay" value used in the EIGRP metric calculation will be inaccurate on the 256 kb/s
serial interface.
C. The amount of bandwidth used for EIGRP routing protocol traffic on the 256 kb/s link can become
excessive.
D. EIGRP can load balance between the two serial links only if the variance is set to 2 or higher.
E. Unequal cost load balancing will be disabled.
Answer: C
By default, EIGRP will limit itself to using no more than 50% of the available bandwidth. The primary
benefit of controlling EIGRP's bandwidth usage is to avoid losing EIGRP packets, which could occur
when EIGRP generates data faster than the line can absorb it.
More on: Link1
CCNP Route 642-902 Questions/Answers - EIGRP
2013 10
Refer to the exhibit. Your company has just implemented this EIGRP network. A network administrator
came to you for advice while trying to implement load balancing across part of their EIGRP network.
If the variance value is configured as 2 on all routers and all other metric and K values are configured to
their default values, traffic from the Internet to the data center will be load balanced across how many
paths?
A. 1
B. 2
C. 3
D. 4
E. 5
Answer: B
We can see that point of interest is Router A, because from it there are multiple paths to the Data Center
network.
We have Unequal Load Balancing because variance is higher than 1 (in our case variance is 2). Here we
have two conditions that has to be satisfied:
- Route must be loop free, so the best metric (the AD) learned from the next router must be less than the
local best metric (the current FD).
- Metric of the entire path (the FD of the alternative route) must be lower than the variance multiplied by
the local best metric (the current FD).
For easier computation it is better to put all information in the table. Next table contains all information
related to get the answer of the question.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 11
Path Feasible Distance
(FD)
Advertised Distance
(AD)
Successor
Feasible Successor (FS)
AD(FS)<FD (S)
Unequal Load Balancing Path
(variance 2)
FD(Feasible)<2*FD (S)
A-B-C-H 70 30
A-D-E-H 30 20 S S
A-F-G-H 60 40
A-B-E-H 60 20 FS1: 20<30
A-B-E-F-G-H 100 60
A-D-E-F-G-H 70 60
A-F-E-H 40 20 FS2: 20<30 Feasible: 40<2*30
A-F-E-B-C-H 70 50
A-D-E-B-C-H 60 50
We have one successor route that will be in the routing table. After configuring router A with variance 2
in routing table we will got another route called feasible (A-F-E-H). That means that we will got load
balancing through two paths.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 12
Refer to the exhibit. A Boston company bought the assets of a New York company and is trying to route
traffic between the two data networks using EIGRP. The show command output shows that traffic will
not flow between the networks. As a network consultant, you were asked to modify the configuration and
certify the interoperability of the two networks. For traffic to flow from subnet 172.16.8.0/24 to the
172.16.16.0/24 subnet, which configuration change do you recommend?
N2(config)#router eigrp 100 N2(config-router)#network 172.16.8.0
N2(config-router)#network 172.16.10.0
B2(config)#router eigrp 100 B2(config-router)#network 172.16.16.0
B2(config-router)#network 172.16.18.0
N1(config)#router eigrp 100 N1(config-router)#network 172.16.10.0
N1(config-router)#network 10.10.24.0
N1(config-router)#network 192.168.20.0
B1(config)#router eigrp 100 B1(config-router)#network 172.16.18.0
B1(config-router)#network 10.10.18.0
B1(config-router)#network 182.168.30.0
A. Turn off autosummarization on routers N1 and B1.
B. Add IP summary addresses to the Internet-pointing interfaces of routers N1 and B1.
C. Turn off autosummarization on routers N2 and B2.
D. Add wildcard masks to the network commands on routers N2 and B2.
Answer: A
If we look at the N1 and B1 router we can see that they will advertise the same summary routes:
10.0.0.0/8 and 172.16.0.0/16. Because we will have discontigious network, problem will occur and there
will be no communication between N1 and B1. If we try to solve this issue with manual summarization,
isn’t going to help.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 13
To solve this we have to use commands:
N1(config)#router eigrp 100
N1(config-router)#no auto-summary
B1(config)#router eigrp 100
B1(config-router)# no auto-summary
to turn off autosummarization on N1 and B1. After this routes to networks connected on N1 and B1 will
be advertised between the routers and communication between the networks will be established.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 14
Refer to the exhibit. A Boston company bought the assets of a New York company and is trying to route
traffic between the two data networks using EIGRP over EoMPLS. As a network consultant, you were
asked to verify the interoperability of the two networks.
From the show ip route command output, what can you tell the customer about the traffic flow between
the subnet in New York (172.16.8.0/24) and the subnets in Boston (172.16.16.0/24 and 10.10.16.0/24)?
Gateway of Last resort is not set
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
D 172.16.8.0/24 (90/30720) via 172.16.10.2, 00:20:43, FastEthernet0/0
C 172.16.10.0/24 is directly connected, FastEtherenet0/0
D 172.16.0.0/16 is a summary, 00:19:05, Null0
C 192.168.20.0/24 is directly connected, FastEthernet0/1 D 10.0.0.0/8 (90/30720) via 192.168.20.2, 00:14:51, FastEthernet0/1
Gateway of Last resort is not set
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
D 172.16.8.0/24 (90/30720) via 172.16.18.2, 00:06:04, FastEthernet0/0.172
C 172.16.18.0/24 is directly connected, FastEtherenet0/0.172 D 172.16.0.0/16 is a summary, 00:50:05, Null0
C 192.168.20.0/24 is directly connected, FastEthernet0/1
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks D 10.0.0.0/8 is a summary, 00:15:51, Null0
D 10.10.16.0/24 (90/30720) via 10.10.18.3, 00:04:24, FastEthernet0/0.10
C 10.10.18.0/24 is directly connected, FastEtherenet0/0.10
A. Traffic is flowing between the 172.16.8.0 subnet and subnets 172.16.16.0 and 10.10.16.0 and no
configuration changes are needed.
B. Auto-summary must be disabled on N1 and B1 before traffic can flow between the 172.16.8.0 subnet
and subnets 172.16.16.0 and 10.10.16.0.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 15
C. Traffic will flow between the 172.16.8.0 subnet and 172.16.16.0 without any further configuration
changes. However, auto-summary must be disabled on N1 and B1 before traffic can flow between the
172.16.8.0 subnet and the 10.10.16.0 subnet.
D. Auto-summary must be disabled on N1 and B1 before traffic can flow between the 172.16.8.0 subnet
and the 172.16.16.0 subnet. However, traffic will flow between the 172.16.8.0 subnet and 10.10.16.0
without any further configuration changes.
Answer: B
If we look at the N1 and B1 router we can see that they will advertise the same summary route
172.16.0.0/16. Because we will have discontigious network, problem will occur and there will be no
communication between N1 and B1. If we try to solve this issue with manual summarization, isn’t going
to help.
To solve this we have to use commands:
N1(config-router)#no auto-summary
B1(config-router)# no auto-summary
to turn off autosummarization on N1 and B1. After this routes to networks connected on N1 and B1 will
be advertised between the routers and communication between the networks will be established.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 16
Which three EIGRP routes will be installed for the 172.17.3.128/25 and 172.17.2.0/24 networks? (Choose
three)
Core1#show ip eigrp topology all-links
IP EIGRP Topology table for AS(65001)/ID(172.17.10.1)
Codes:P-Passive, A-Active, U-Update, Q-Query, R-Reply, r-reply Status, s-sia Status
P 172.17.3.128/25, 2 successors, FD is 30720, semo 9 via 172.17.10.2 (30720/28160), FastEtehrnet0/1
via 172.17.3.2 (30720/28160), FastEtehrnet0/3
P 10.140.0.0/24, 1 successors, FD is 156160, semo 16 via 172.17.3.2 (156160/128256), FastEtehrnet0/3
via 172.17.10.2 (157720/155160), FastEtehrnet0/1
P 172.17.10.0/24, 1 successors, FD is 28160, semo 1 via Connected FastEthernet0/1
P 172.17.0.0/30, 1 successors, FD is 20514560, semo 15
via 172.17.1.1 (20514560/205122000), FastEtehrnet0/2 via 172.17.10.2 (20516120/20513560), FastEtehrnet0/1
P 172.17.1.0/24, 1 successors, FD is 28160, semo 2
via Connected FastEthernet0/2 P 172.17.2.0/24, 1 successors, FD is 30720, semo 8
via 172.17.10.2 (30720/28160), FastEtehrnet0/1
via 172.17.3.2 (33280/30720), FastEtehrnet0/3 P 172.17.3.0/25, 1 successors, FD is 28160, semo 3
via Connected FastEthernet0/3
Core1#
A. 172.17.3.128.25 [90/28160] via 172.17.1 2, 01:26:35, FastEthernet0/2
B. 172.17.3.128/25 [90/30720] via 172.17.3.2, 01:26:35, FastEthemet0/3
C. 172.17.3.128/25 [90/30720] via 172.17.10.2, 01:26:35, FastEthernet0/1
D. 172.17.2.0/24 [90/30720] via 172.17.10.2, 02:10:11, FastEthernet0/1
E. 172.17.2.0/24 [90/28160] via 172.17.10.2, 02:10:11, FastEthernet0/1
F. 172.17.2.0/24 [90/33280] via 172.17.3.2, 02:10:11, FastEthernet0/3
Answer: B, C, D
For 172.17.3.128/25 network:
We have 2 successor routes in the topology table. That means both routes will be in the routing table.
For 172.17.2.0/24 network:
We have 1 successor routes in the topology table. That means just this route will be in the routing table.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 17
These routes are indicated in the following picture that gives output of show ip eigrp topology all-links
command.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 18
Refer to the exhibit. EIGRP is configured on all routers in the network. On the basis of the output
provided, which statement is true?
R1#show running-config <output omitted>
key chain troy key 1
key-string 0987654321
key 2 key-string 1234567890
<output omitted>
interface FastEthernet0/0 ip address 10.10.10.1 255.255.255.0
ip authentication mode eigrp 1 md5
ip authentication key-chain eigrp 1 troy <output omitted>
router eigrp 1
network 10.0.0.0 no auto-summary
R2#show running-config <output omitted>
key chain boston key 1
key-string 0987654321
key 2 key-string 1234567890
<output omitted>
interface GigabitEthernet0/0 ip address 10.10.10.2 255.255.255.0
ip authentication mode eigrp 1 md5
ip authentication key-chain eigrp 1 boston !
interface GigabitEthernet0/1
ip address 172.16.1.1 255.255.255.0 ip authentication mode eigrp 1 md5
ip authentication key-chain eigrp 1 boston
<output omitted>
router eigrp 1
network 10.0.0.0
network 172.16.0.0 no auto-summary
R3#show running-config <output omitted>
key chain schedulle key 1
key-string 0987654321
key 2 key-string 1234567890
<output omitted>
interface GigabitEthernet0/1 ip address 172.16.1.2 255.255.255.0
ip authentication mode eigrp 1 md5
ip authentication key-chain eigrp 1 schedulle <output omitted>
router eigrp 1
network 172.16.0.0 no auto-summary
A. Because the key chain names do not match, router R1 will not be able to ping routers R2 and R3.
B. Because the key strings do not match, router R1 will not be able to ping routers R2 and R3.
C. Because authentication is misconfigured on interfaces Gi0/0 and Gi0/1 on router R2, router R1 will not be able to
ping routers R2 and R3.
D. Because autosummarization needs to be turned on for EIGRP on all routers, router R1 will not be able to ping
routers R2 and R3.
E. Router R1 will be able to ping routers R2 and R3.
Answer: E
-----
To configure MD5 authentication for EIGRP, we have to complete the following steps:
CCNP Route 642-902 Questions/Answers - EIGRP
2013 19
Step 1: Enter configuration mode for the interface on which you want to enable authentication.
Step 2: Specify MD5 authentication for EIGRP packets using the ip authentication mode eigrp
autonomous-system md5 interface configuration command. The autonomous-system is the EIGRP
autonomous system number in which authentication is to be used.
Step 3: Enter the key-chain configuration mode for the key chain (that you will later configure on the
interface) using the key chain name-of-chain global configuration command.
Step 4: Identify a key ID to use and enter configuration mode for that key (the key-chain-key
configuration mode) using the key key-id key-chain configuration command. The key-id is the ID number
of an authentication key on a key chain. The range of keys is from 0 to 2147483647. The key ID numbers
need not be consecutive.
Step 5: Identify the key string (the password) for this key using the key-string key key-chain-key
configuration command. The key is the authentication key-string that is to be used to authenticate sent and
received EIGRP packets. The key string can contain from 1 to 80 uppercase and lowercase alphanumeric
characters, except that the first character cannot be a number. The key string for a given key ID must be
the same on neighboring routers and is case sensitive.
Step 6: Optionally specify the time period during which this key will be accepted for use on received
packets using the accept-lifetime start-time {infinite | end-time | duration seconds} key-chain-key
configuration command.
Step 7: Optionally specify the time period during which this key can be used for sending packets using
the send-lifetime start-time {infinite|end-time|duration seconds} key-chain-key configuration command.
Step 8: Enable the authentication of EIGRP packets with a key specified in a key chain by using the ip
authentication key-chain sigrp autonomous-system name-of-chain interface configuration command. The
autonomous-system parameter specifies the EIGRP configuration command. The autonomous-system
parameter specifies the EIGRP autonomous system number in which authentication is to be used. The
name-of-chain parameter specifies the name of the configured key chain from which a key is to be
obtained for this interface.
-----
As we can see from show running-config outputs on R1, R2 and R3 key chain name is configured for all
tree routers (key chain troy for R1, key chain boston for R2 and key chain schedule for R3). Key-ids are
also configured on R1, R2 and R3 (key 1 and key 2 for all three routers). Key strings are configured on
R1, R2 and R3 (for key 1 there is key-string 0987654321and for key 2 there is key-string 1234567890 for
all three routers).
As we can see above (step 5) key string for a given key ID must be the same on neighboring routers. That
is accomplished in our case.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 20
Also Step 2 and step 8 are properly configured on all routers.
Communication will be normal between routers. Neighbor relations will be established (same EIGRP AS
number; no auto summary; - on all routers).
CCNP Route 642-902 Questions/Answers - EIGRP
2013 21
Which is the correct command format to configure EIGRP summary route?
A. ip auto-summary as-number address mask
B. ip summary-address as-number address mask
C. ip auto-summary eigrp as-number address mask
D. ip summary-route eigrp as-number address mask
E. ip summary-address eigrp as-number address mask
Answer: E
To turn off automatic summarization, use the no auto-summary router configuration command.
Use the ip summary-address eigrp as-number address mask [admin-distance] interface configuration
command to manually create a summary route at an arbitrary bit boundary, as long as a more specific
route exists in the routing table.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 22
Which is the most effective technique to contain EIGRP queries?
A. route summarization
B. configuring route filters
C. using a hierarchical addressing scheme
D. establishing separate autonomous systems
Answer: A
The network manager must determine the information necessary to properly route user traffic to the
appropriate destination. The amount of information needed by the remote routers to achieve the desired
level of path selection must be balanced against the bandwidth used to propagate this information. To
achieve maximum stability and scalability, the remote routers can use a default route to reach the core. If
some specific networks need knowledge of more routes to ensure optimum path selection, the
administrator must determine whether the benefits of propagating the additional routing information
outweigh the additional bandwidth required to achieve this goal.
In a properly designed network, each remote site has redundant WAN links to separate distribution sites.
If both distribution sites pass a default route to the remote sites, the remote sites load balance to all
networks behind the distribution site routers. This maximizes bandwidth utilization and allows the remote
router to use less CPU and memory, which means that a smaller and less-expensive remote router can be
used at that site.
If the remote site can see all routes, the router can select a path that is best to reach a given network.
However, depending on the number of routes in the internetwork and the amount of bandwidth
connecting the remote site to the distribution sites, this approach can mean that higher-bandwidth links or
large routers are needed to handle the additional overhead.
After you determine the minimum routing requirements, you can make EIGRP more scalable. Two of the
best options are the following:
- Configure route summarization using the ip summary-address eigrp command on the outbound
interfaces of the appropriate routers.
- Configure the remote routers as stub EIGRP routers.
Other methods to limit query range include route filtering and interface packet filtering. For example, if
specific EIGRP routing updates are filtered to a router and that router receives a query about those filtered
(blocked) networks, the router indicates that the network is unreachable and does not extend the query
any further.
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A network administrator is troubleshooting an EIGRP configuration across a discontiguous network. What must the
administrator do to ensure the routers have the correct routing information?
A. Nothing, EIGRP supports discontiguous networks by default.
B. The administrator must disable automatic summarization with the command no auto-summary.
C. The administrator must enable manual summarization with the command ip summary-address.
D. The administrator must enable classless routing with the command ip classless.
E. The administrator must specify a default network with the command ip default-network.
Answer: B
If we want to solve connectivity issues in the discontiguous network we have to disable auto summarization on
routers.
CCNP Route 642-902 Questions/Answers - EIGRP
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What is the purpose of the eigrp stub configuration command?
A. To increase scalability by limiting the EIGRP query range.
B. To reduce the size of the routing table by blocking the D EX (External EIGRP) routes into the EIGRP stub
router.
C. To reduce the convergence time by enabling the EIGRP stub router to propagate the EIGRP queries from the
EIGRP hub router.
D. To reduce the convergence time by enabling the EIGRP stub router to also perform query requests to the EIGRP
hub router.
Answer: A
A stub router indicates in the hello packet to all neighboring routers its status as a stub router. Any router
that receives a packet informing it of its neighbor’s stub status does not query the stub router for any
routes. Therefore, a router that has a stub peer does not query that peer.
Thus, it is important to note that stub routers are not queried. Instead, hub routers connected to the stub
router answer the query on behalf of the stub router.
A router configured as a stub with the eigrp stub command shares information about connected and
summary routes with all neighbor routers by default.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 25
Refer to the exhibit. EIGRP is enabled on all routers on the network. What additional configuration is
required for the routers connected over the Frame Relay multipoint interfaces to compensate for a low-
speed NBMA connection?
A. Configure the EIGRP hello interval on all Frame Relay interfaces to 5 seconds.
B. Configure the EIGRP hello interval on all Frame Relay interfaces to 60 seconds.
C. Configure the EIGRP hold time on all Frame Relay interfaces to 15 seconds.
D. Configure the EIGRP hold time on all Frame Relay interfaces to 180 seconds.
E. Configure the bandwidth on all EIGRP Frame Relay interfaces to the committed information rate (CIR).
F. Configure the bandwidth on all EIGRP Frame Relay interfaces to the lowest CIR multiplied by the number of
PVCs for the multipoint connection.
Answer: F
Committed information rate or CIR in a Frame relay network is the average bandwidth for a virtual
circuit guaranteed by an ISP to work under normal conditions. At any given time, the bandwidth should
not fall below this committed figure. The bandwidth is usually expressed in kilobits per second (kbit/s).
When we are configuring multipoint interfaces for Frame Relay bandwidth is shared equally by all
neighbors. EIGRP uses bandwidth command on the physical interface divided by the number of Frame
Relay neighbors connected on that physical interface to get the bandwidth attributed to each neighbor.
EIGRP configuration should reflect the correct percentage of the actual available bandwidth on the line.
Different CIR values on topology can influence on configuration. Different CIR values often require a
hybrid configuration that blends characteristics of point-to-point circuits with multipoint circuits. When
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configuring multipoint interfaces you have to configure the bandwidth to represent the minimum CIR
times the number of circuits:
Bandwidth = Lowest CIR given by ISP * Number of VC (virtual circuits).
Example: If we got CIR for one VC of 56 and CIR for other 4 VC is 256, then lowest CIR is 56 and
bandwidth is:
Bandwidth = Lowest CIR given by ISP * Number of VC (virtual circuits) = 56*(4+1) = 56 * 5 = 280
CCNP Route 642-902 Questions/Answers - EIGRP
2013 27
Based on the topology shown in the network diagram, what optional EIGRP configurations will be
required in order to achieve full connectivity within AS 100?
A. Use the EIGRP no auto-summary command on R1 and R2.
B. Use the EIGRP no auto-summary command on R3 and R4.
C. Use the passive interface on the R1 and R2 interface that connects to the 10.1.1.0/24 and 10.1.2.0/24 subnet
respectively.
D. Use the passive interface command between the R3 and R1 connection and between the R3 and R2 connection.
E. Use the variance command on R3.
Answer: A
When you use the passive-interface command with EIGRP, hello messages are not sent out of the
specified interface. Neighboring router relationships do not form with other routers that can be reached
through that interface (because the hello protocol is used to verify bidirectional communication between
routers). Because no neighbors are found on an interface, no other EIGRP traffic is sent. Passive interface
usually is used in case of redistribution on border router where, on particular interface you have to disable
routing from specific routing protocol (RIP, EIGRP, OSPF). So, this is not an option in our case.
Variance is used if we want to perform unequal load balancing. In our case there are no alternative routes
to R1, to R2 and to R4 from R3. It is not usable solution also for our needs.
If we have auto summarization (that is enabled by default) on routers R1 and R2 then, both routers will
advertise same summary route for 10.0.0.0/8 network. This can lead that traffic be send to the wrong
router. Because of that these routes will be removed from routing table in routers in the network. To
prevent this we have to use EIGRP no auto-summary command on R1 and R2.
More on: Link1
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2013 28
Which command should you issue first to configure EIGRP for IP?
A. ip eigrp routing
B. router eigrp process-id
C. ip eigrp autonomous-system-number
D. router eigrp autonomous-system-number
Answer: D
Multiple network layer support - EIGRP supports IP Version 4 (IPv4), IP Version 6 (IPv6), AppleTalk,
and Novell NetWare Internetwork Packet Exchange (IPX) using protocol-dependent modules that are
responsible for protocol requirements specific to the network layer. EIGRP’s rapid convergence and
sophisticated metric offer superior performance and stability when implemented in IP, IPv6, IPX, and
AppleTalk networks.
To create an EIGRP routing IP process you have to use the following command:
Router(config)# router eigrp autonomous-system-number /Enables an EIGRP routing process in
global configuration mode.
More on: Link1
CCNP Route 642-902 Questions/Answers - EIGRP
2013 29
A network administrator is managing a hub-and-spoke network with EIGRP routing that has been enabled. The hub
router is trying to query a remote router. However, delays are occurring that are caused by certain paths being stuck
in active (SIA). How should the administrator configure EIGRP in order to limit the scope of the query range and
prevent SIA from occurring?
A. Configure the hub router with a scope limit of 1.
B. Configure the remote router with a scope limit of 1.
C. Configure the hub to indicate that the remote router is a stub router.
D. Configure the hub and remote router as stub routers.
E. Configure the remote router as a stub router.
F. Disable the SIA feature of EIGRP on the remote router.
Answer: E
Limiting the scope of query propagation through the network (the query range), also known as query
scoping, helps reduce incidences of SIA (Stuck-in-Active). Keeping the query packets close to the source
reduces the chance that an isolated failure in another part of the network will restrict the convergence
(query/reply) process.
In hub-and-spoke network spoke (remote) routers will be configured as stub with commands:
Spoke(congfig)#router eigrp 1
Spoke(config)#eigrp stub
, if we use EIGRP AS 1.
Configuring spoke routers as stub we are reducing the bandwidth overloading and chance routes to
become SIA.
Note: There is another method for limiting the scope of query propagation through the network (the query
range) for our scenario. That is using route-summarization. If we configure route summarization on hub
router with command:
Hub(config-if)#ip summary-address eigrp ip_address_of_LAN netmask_for_LAN
on its outbound interfaces towards spoke routers, then summary route for LAN will be advertised.
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Refer to the Exhibit. Routers in the Diagram are configured with EIGRP. If RB and RC fail, which action
will RA take with respect to the HQ network?
A. RA will automatically route packets via RD to the HQ network.
B. RA will place the route via RD into the hold down state.
C. RA will go into the active state for all routers.
D. RA will go into the active state for the route to HQ network.
Answer: D
Successor (S) is a neighboring router used for packets forwarding that has a least-cost path to a
destination that is guaranteed not to be part of the routing loop. If EIGRP topology has many entries that
have equal-cost FD to a given destination network, all successor (up to 4 by default) for that destination
network will be installed in the routing table.
Feasible Successor (FS) is router that provides backup route. The route through the FS must be loop free.
These FS routes are kept in the topology table. The topology table can retain multiple FS routes for a
destination. To qualify as an FS a next-hop router must have AD less than the FD of current successor
route for the particular network. This is known as feasibility condition.
In our case:
To get closer view of the routes we will use following picture with marking (added with red) for the
routers.
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For easier computation it is better to put all information in the table. Next table contains all information
related to get the answer of the question.
Path Feasible Distance
(FD)
Advertised Distance
(AD)
Successor
Feasible Successor
(FS) AD(FS)<FD (S)
RA-RB-R40 40 30 30<31 --- FS
RA-RC-R10-R40 31 21 S
RA-RD-R20-R30-R40 230 220
We have one successor route that will be in the routing table. We have one feasible successor route that
will be in topology table.
That is when network is stabile. But, regarding condition above, if RB and RC fail, then routes through
RB and RC are not valid anymore.
When a router loses a route it looks at the topology table for an FS. If there is FS router will use it as
successor route and put it in routing table, without recalculation. In our case successor and feasible
successor routes are not valid. That means that route will go into active state and will be route
recomputation in RA for route to HQ network.
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Refer to the following.
Router # sh ip route eigrp 13.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
D 13.0.0.0/8 is a summary, 00:00:32, Null0
What happens to packets that are forwarded from the 13.0.0.0/8 network to the Null0 interface?
A. Flagged
B. Accepted
C. Summarized
D. Dropped
Answer: D
When there is summary route in the routing table, it points to the Null0 interface. All traffic that is destined to this
summary network will be dropped.
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2013 33
Based on the exhibited command output, which two statements are true? (Choose two.)
R1# show ip eigrp topology
IP-EIGRP Topology Table for AS(24)/ID(1.1.1.1)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - Reply status, s – sia Status
P 10.2.1.0/24, 1 successors, FD is 28160
via Connected, FastEthernet0/0
P 10.1.1.0/24, 1 successors, FD is 20512000 via Connected, Serial0/0
P 172.20.0.0/16, 1 successors, FD is 40992000
via 10.1.1.2 (40992000/40480000), Serial0/0 P 172.16.0.0/16, 1 successors, FD is 23072000
via 10.1.1.2 (23072000/2560256), Serial0/0
P 172.17.0.0/16, 1 successors, FD is 25632000 via 10.1.1.2 (25632000/5120256), Serial0/0
P 172.18.0.0/16, 1 successors, FD is 32032000
via 10.1.1.2 (32032000/11520256), Serial0/0 A 172.19.0.0/16, 1 successors, FD is Inaccessible, Q
2 replies, active never, query-origin: Successor Origin
via 10.1.1.3 (391248640/390736640), r, Serial0/0 Remaining replies:
via 10.1.1.2, r, Serial0/0
A. The EIGRP network is stable.
B. The router at 10.1.1.3 has not replied to the R1 query packet.
C. The route to 172.19.0.0/16 is undergoing recomputation.
D. The route to 172.19.0.0/16 is stuck-in-active.
E. R1 has sent a query packet to 10.1.1.2.
Answer: C, E
Codes that are used in output of show ip topology table:
- Passive (P) - This network is available, and installation can occur in the routing table. Passive is the
correct state for a stable network, indicating that no EIGRP computations are being performed for this
route.
- Active (A) - This network is currently unavailable, and installation cannot occur in the routing table.
Active means that outstanding queries exist for this network, which indicates that EIGRP computations
are being performed for this route.
- Update (U) - This network is being updated (indicating that an update packet is being sent). This code
also applies if the router is waiting for an acknowledgment for this update packet.
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- Query (Q) - There is an outstanding query packet for this network, indicating that a query packet was
sent. This code also applies if the router is waiting for an acknowledgment for a query packet.
- Reply (R) - The router is generating a reply for this network, indicating that a reply packet was sent, or
is waiting for an acknowledgment for the reply packet.
- Reply status (r) - Indicates the flag that is set after the software has sent a query and is waiting for a
reply.
- Stuck-in-active (s) - There is an EIGRP convergence problem for this network. (The ―Stuck-in-Active
Connections in EIGRP‖ section, later in this chapter, describes this problem and how it can be prevented.)
In our example we have that 172.19.0.0/16 network is in active state (A) and that R1 waits reply for the
query that is sent to 10.1.1.2 (r is indicating reply status).
----- A 172.19.0.0/16, 1 successors, FD is Inaccessible, Q
2 replies, active never, query-origin: Successor Origin
via 10.1.1.3 (391248640/390736640), r, Serial0/0 Remaining replies:
via 10.1.1.2, r, Serial0/0
CCNP Route 642-902 Questions/Answers - EIGRP
2013 35
Which show command will display the two values used in the calculation of the EIGRP metric?
A. show protocol
B. show ip eigrp interface
C. show interface
D. show ip eigrp neighbor
Answer: C
DUAL selects routes based on the EIGRP composite metric. Five criteria are associated with the EIGRP
composite metric, but EIGRP uses only two by default:
- Bandwidth - The smallest (slowest) bandwidth between the source and destination
- Delay - The cumulative interface delay along the path
The following criteria, although available, are not commonly used, because they typically result in
frequent recalculation of the topology table:
- Reliability - The worst reliability between the source and destination, based on keepalives.
- Loading - The worst load on a link between the source and destination based on the packet rate and the
interface’s configured bandwidth.
- Maximum transmission unit (MTU) - The smallest MTU in the path. (MTU is included in the EIGRP
update but is actually not used in the metric calculation.)
Information needed to do computations of EIGRP composite metric can be found in show interface command.
Example:
Router# show interfaces
Ethernet 0 is up, line protocol is up
Hardware is MCI Ethernet, address is 0000.0c00.750c (bia 0000.0c00.750c)
Internet address is 10.108.28.8, subnet mask is 255.255.255.0 MTU 1500 bytes, BW 10000 Kbit, DLY 100000 usec, rely 255/255, load 1/255
Encapsulation ARPA, loopback not set, keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 4:00:00 Last input 0:00:00, output 0:00:00, output hang never
Last clearing of "show interface" counters 0:00:00
Output queue 0/40, 0 drops; input queue 0/75, 0 drops Five minute input rate 0 bits/sec, 0 packets/sec
Five minute output rate 2000 bits/sec, 4 packets/sec 1127576 packets input, 447251251 bytes, 0 no buffer
Received 354125 broadcasts, 0 runts, 0 giants, 57186* throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 5332142 packets output, 496316039 bytes, 0 underruns
0 output errors, 432 collisions, 0 interface resets, 0 restarts
CCNP Route 642-902 Questions/Answers - EIGRP
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It is important to note that the format of the delay and bandwidth values is different from those displayed
by the show interfaces command, as follows:
- The EIGRP delay value is the sum of the delays in the path, in tens of microseconds, multiplied by
256. The show interfaces command displays delay in microseconds.
- The EIGRP bandwidth is calculated using the minimum bandwidth link along the path, represented in
kilobits per second (kbps). is divided by this value, and then the result is multiplied by 256.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 37
Refer to the exhibit. If the configuration shown below is added to RTA, which three route entries will
EIGRP advertise to neighboring routers? (Choose three.)
router eigrp 10
network 10.0.0.0 eigrp stub
RTA#show ip route
… C 10.1.3.0/24 is directly connected, Serial2
D 10.1.2.0/24 [90/10537472] via 10.1.1.2, 00:23:24, Serial1
D 10.0.0.0/8 is a summary, 00:23:20, Null0 C 10.1.1.0/24 is directly connected, Serial1
S 192.168.20.0/24 is directly connected, Ethernet0
A. 10.1.3.0/24
B. 10.1.2.0/24
C. 10.0.0.0/8
D. 10.1.1.0/24
E. 192.168.20.0/24
Answer: A, C, D
In regard of information in routing table we are able to draw network topology shown below.
Now when we add on RTA:
router eigrp 10
network 10.0.0.0
eigrp stub
CCNP Route 642-902 Questions/Answers - EIGRP
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We will configure EIGRP AS 10 for network 10.0.0.0, which by default is configured with auto-
summarization. Also this router is configured as stub (remote router), that makes to advertise just
connected and summary routes.
Now RTA will forward to the neighbor router route to 10.1.3.0/24 that is directly connected to it; 10.1.1.0/24
that connects to the neighbor router and summary route that points to the Null0 interface. Route to 192.168.20.0/24
network isn’t going to be advertised to the neighbor router because it is not defined in configuration for EIGRP AS
10 network.
CCNP Route 642-902 Questions/Answers - EIGRP
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Refer to the exhibit. Network administrators have set up a hub and spoke topology with redundant
connections using EIGRP. However, they are concerned that a network outage between Router R1 and
Router R2 will cause traffic from the 10.1.1.x network to the 10.1.2.x network to traverse the remote
office links and overwhelm them. What command should be used to configure the spoke routers as
EIGRP stub routers that will not advertise connected networks, static routes, or summary addresses?
A. eigrp stub
B. eigrp stub receive-only
C. eigrp stub connected static
D. no eigrp stub connected static
E. No additional command is needed beyond a default EIGRP configuration.
Answer: B
Table 2-13 describes the four optional keywords that can be used with the eigrp stub command (advertise
just connected and summary routes) to modify this behavior.
Table 2-13. eigrp stub Command Parameters
Parameter Description
receive-only - The receive-only keyword restricts the router from sharing any of its routes with any other
router within an EIGRP autonomous system. This keyword does not permit any other keyword to be
specified, because it prevents any type of route from being sent. Use this option if there is a single
interface on the router.
connected - The connected keyword permits the EIGRP stub routing feature to send connected routes. If
a network command does not include the connected routes, it might be necessary to redistribute
CCNP Route 642-902 Questions/Answers - EIGRP
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connected routes with the redistribute connected command under the EIGRP process. This option is
enabled by default and is the most widely practical stub option.
Static - The static keyword permits the EIGRP stub routing feature to send static routes. Redistributing
static routes with the redistribute static command is still necessary.
summary - The summary keyword permits the EIGRP stub routing feature to send summary routes. You
can create summary routes manually with the ip summary-address eigrp command or automatically at a
major network border router with the auto-summary command enabled. This option is enabled by
default.
redistributed - The redistribute option permits the EIGRP stub routing feature to send redistributed
routes. Redistributing routes with the redistribute command is still necessary.
The optional parameters in this command can be used in any combination, with the exception of the
receive-only keyword. If any of the keywords (except receive-only) is used individually, the connected
and summary routes are not sent automatically.
Because we don’t need routing information to be sent from Spoke routers to the Hub routers, we need to
use command:
Spoke(config-router)#eigrp stub receive-only
CCNP Route 642-902 Questions/Answers - EIGRP
2013 41
Which three statements are true regarding EIGRP? (Choose three.)
A. By default, EIGRP performs auto-summarization across classful network boundaries.
B. EIGRP uses an area hierarchy to increase network scalability.
C. To speed convergence, EIGRP attempts to maintain a successor and feasible successor path for each destination.
D. EIGRP uses hellos to establish neighbor relationships.
E. By default, EIGRP uses the Dijkstra algorithm to determine the best path to a destination network based on
bandwidth and delay.
Answer: A, C, D
- EIGRP performs an auto-summarization each time it crosses a border between two different major
networks.
EIGRP auto-summarizes at classful network boundaries. This means that if one interface is in 1.1.0.0/16
and another interface is in 2.2.2.0/24 then EIGRP will summarize the networks before advertising them
out of the opposite interface. This is because each subnet belongs to a separate major classful network:
1.0.0.0/8 and 2.0.0.0/8 in this case. However if you have one interface in 2.2.2.0/24 and another interface
in 2.3.0.0 then auto-summarization will not take affect because both interfaces belong to the major
network 2.0.0.0/8. EIGRP may auto-summarize for some networks and not others in the same EIGRP
process.
- Fast convergence - EIGRP uses an algorithm called the Diffusing Update Algorithm (DUAL). This
algorithm guarantees loop-free operation at every instant throughout a route computation and allows all
routers involved in a topology change to synchronize at the same time. Routers that are not affected by
topology changes are not involved in recomputations. DUAL provides a system for routers to not only
calculate the best current route to each subnet, but also to calculate alternative routes that could be used if
the current route fails. The alternate route, called the feasible successor route, is guaranteed to be loop-
free, so convergence can happen quickly. Because of DUAL, the convergence time of EIGRP rivals that
of other existing routing protocols.
- EIGRP uses the following five packet types:
Hello/Acks - Hello packets are sent for neighbor discovery/recovery and do not require
acknowledgment.
Updates - Update packets are used to convey reachability of destinations. When a new neighbor
is discovered, update packets are sent so that the neighbor can build up its topology table.
CCNP Route 642-902 Questions/Answers - EIGRP
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Queries - Query packets are sent when a destination has no feasible successors.
Replies - Reply packets are sent when a destination has no feasible successors and are sent in
response to query packets to instruct the originator not to recompute the route because feasible
successors exist.
Requests - Request packets are used to get specific information from one or more neighbors.
More on: Link1; Link2
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2013 43
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Hotspot – EIGRP
Refer to the exhibit. FubGames Incorporated is a worldwide gaming provider. The network uses EIGRP
as 1st routing protocol throughout the corporation. The network administrator does not understand the
convergence of EIGRP. Using the output of the show ip eigrp topology all-links command, answer the
administrator’s questions.
1.Which two networks does the Switch1 device have feasible successors for? (Choose two)
A. 172.18.0.0/30
B. 172.18.1.0/24
C. 172.18.2.0/24
D. 172.18.3.0/25
E. 172.18.3.128/25
F. 10.24.0.0/24
Answer: A, F
To understand the output of the “show ip eigrp topology all-links” command, let’s analyze an entry (we
choose the second entry because it is better for demonstration than the first one)
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The first box tells us there is only 1 successor for the path to 10.24.0.0/24 network but there are 2 boxes
below. So we can deduce that one box is used for successor and the other is used for another route to that
network. Each of these two boxes has 2 parameters: the first one (―156160″ or ―157720″) is the Feasible
Distance (FD) and the second (―128256″ or ―155160″) is the Advertised Distance (AD) of that route.
The next thing we want to know is: if the route via 172.18.10.2 (157720/155160) would become the
feasible successor for the 10.24.0.0/24 network.
To figure out, we have to compare the Advertised Distance of that route with the Feasible Distance of the
successor’s route, if AD < FD then it will become the feasible successor. In this case, because AD
(155160) < FD (156160) so it will become the feasible successor. Therefore we can conclude the network
10.24.0.0/24 has 1 feasible successor.
After understanding the output, let’s have a look at the entire output:
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Because the question asks about feasible successor so we just need to focus on entries which have more
paths than the number of successor. In this case, we find 3 entries that are in green boxes because they
have only 1 successor but has 2 paths, so the last path can be the feasible successor.
By comparing the value of AD (of that route) with the FD (of successor’s route) we figure out there are 2
entries will have the feasible successor: the first and the second entry. The third entry has AD = FD
(30720) so we eliminate it.
+++++++++++++
2. Which three EIGRP routes will be installed for the 172.18.3.128/25 and 172.18.2.0/24 networks?
(Choose three)
A. D 172.18.3.128/25 [90/28160] via 172.18.1.2, 01:26:35, FastEthernet0/2
B. D 172.18.3.128/25 [90/30720] via 172.18.3.2, 01:26:35, FastEthernet0/3
C. D 172.18.3.128/25 [90/30720] via 172.18.10.2, 01:26:35, FastEthernet0/1
D. D 172.18.2.0/24 [90/30720] via 172.18.10.2, 02:10:11, FastEthernet0/1
E. D 172.18.2.0/24 [90/28160] via 172.18.10.2, 02:10:11, FastEthernet0/1
F. D 172.18.2.0/24 [90/33280] via 172.18.3.2, 02:10:11, FastEthernet0/3
Answer: B, C, D
First indicate the positions of these networks:
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Network 172.18.3.128/25 has 2 successors, therefore the two paths below are both successors. Network
172.18.2.0/24 has only 1 successor, therefore the path lies right under it is the successor. These routes will
be placed in the routing table of the router.
++++++++++++++++
3. Which three networks is the router at 172.18.10.2 directly connected to? (Choose three)
A. 172.18.0.0/30
B. 172.18.1.0/24
C. 172.18.2.0/24
D. 172.18.3.0/25
E. 172.18.3.128/25
F. 172.18.10.0/24
Answer: C, E, F
We can represent on picture information given in topology table:
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Information that is the red marked area is what we need plus link toward Switch1. Successor routes
(represented by the next-hop router that is successor) are point of interest because they got lowest metric
to the Switch1. Other routes can be reached through other routers (feasible successors).
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
CCNP Route 642-902 Questions/Answers - EIGRP
2013 48
Which condition must be satisfied before an EIGRP neighbor can be considered a feasible successor?
A. The neighbor's advertised distance must be less than or equal to the feasible distance of the current
successor.
B. The neighbor's advertised distance must be less than the feasible distance of the current successor.
C. The neighbor's advertised distance must be greater than the feasible distance of the current successor.
D. The neighbor's advertised distance must be equal to the feasible distance of the current successor.
E. The neighbor's advertised distance must be greater than or equal to the feasible distance of the current
successor.
Answer: B
Successor (S) is a neighboring router used for packets forwarding that has a least-cost path to a
destination that is guaranteed not to be part of the routing loop. If EIGRP topology has many entries that
have equal-cost FD to a given destination network, all successor (up to 4 by default) for that destination
network will be installed in the routing table.
Feasible Successor (FS) is router that provides backup route. The route through the FS must be loop free.
These FS routes are kept in the topology table. The topology table can retain multiple FS routes for a
destination. To qualify as an FS a next-hop router must have AD less than the FD of current successor
route for the particular network. This is known as feasibility condition.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 49
Based on the need to limit processing and bandwidth utilization due to dynamic routing protocol
operation, the following routing requirements have been specified for your network.
- partial and incremental routing updates
- only the devices affected by a topology change perform route recomputation
- route recomputation only occurs for routes that were affected
Which dynamic routing protocol should be deployed in your network to best meet these requirements?
A. BGP
B. OSPF
C. IS-IS
D. EIGRP
E. RIPv2
Answer: D
EIGRP is an enhanced IGRP because of its rapid convergence and the guarantee of a loop-free topology
at all times. Features of this protocol include the following:
- Fast convergence— EIGRP uses DUAL to achieve rapid convergence. A router running EIGRP stores
its neighbors’ routing tables so that it can quickly adapt to changes in the network. If no appropriate route
exists in the local routing table and no appropriate backup route exists in the topology table, EIGRP
queries its neighbors to discover an alternative route. These queries are propagated until an alternative
route is found or until it is determined that no alternative route exists.
- Partial updates— EIGRP sends partial triggered updates rather than periodic updates. These updates are
sent only when the path or the metric for a route changes. They contain information about only that
changed link rather than the entire routing table. Propagation of these partial updates is automatically
bounded so that only those routers that require the information are updated. As a result, EIGRP consumes
significantly less bandwidth than IGRP. This behavior is also different from link-state protocol operation,
which sends a change update to all routers within an area.
- Route recomputation - A recomputation occurs when the current route to a destination, the successor,
goes down and there are no feasible successors for the destination. Although recomputation is not
processor intensive, it does affect convergence time, so it is advantageous to avoid unnecessary
recomputations. The router starts the recomputation by sending a query packet to each of its neighboring
routers. If the neighboring router has a route for the destination, it will send a reply packet. If it does not
have a route, it sends a query packet to its neighbors. In this case, the route is also in the active state in the
neighboring router; while a destination is in the active state, a router cannot change the routing table
information for the destination. This process continues. Routers that have no other neighbors and routers
that know that the destination is unreachable reply to queries immediately, indicating the route is
unreachable. When a router receives all replies to its query, it replies to queries from its neighbor, and so
on. If there is at least one topology table entry for the destination after a router has received a reply from
each neighboring router, the destination returns to the passive state, and the router select a successor for it.
If there are no topology table entries for the destination, it is no longer reachable from that router.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 50
Which statement about a non-zero value for the load metric (k2) for EIGRP is true?
A. A change in the load on an interface will cause EIGRP to recalculate the routing metrics and send a
corresponding update out to each of its neighbors.
B. EIGRP calculates interface load as a 5-minute exponentially weighted average that is updated every 5
minutes.
C. EIGRP considers the load of an interface only when sending an update for some other reason.
D. A change in the load on an interface will cause EIGRP to recalculate and update the administrative
distance for all routes learned on that interface.
Answer: C
Load is a value between 1 and 255. A load of 255/255 indicates a completely saturated link. A load of
127/255 represents a 50 percent saturated link. You can see value for load on interface with following
command:
Router# show interfaces
Ethernet 0 is up, line protocol is up
Hardware is MCI Ethernet, address is 0000.0c00.750c (bia 0000.0c00.750c)
Internet address is 131.108.28.8, subnet mask is 255.255.255.0 MTU 1500 bytes, BW 10000 Kbit, DLY 100000 usec, rely 255/255, load 1/255
Encapsulation ARPA, loopback not set, keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 4:00:00 Last input 0:00:00, output 0:00:00, output hang never
Last clearing of "show interface" counters 0:00:00
Output queue 0/40, 0 drops; input queue 0/75, 0 drops Five minute input rate 0 bits/sec, 0 packets/sec
Five minute output rate 2000 bits/sec, 4 packets/sec
1127576 packets input, 447251251 bytes, 0 no buffer Received 354125 broadcasts, 0 runts, 0 giants, 57186* throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
5332142 packets output, 496316039 bytes, 0 underruns 0 output errors, 432 collisions, 0 interface resets, 0 restarts
Input queue: 0/75/0 (size/max/drops); Total output drops: 0
Output queue: 7/64/0 (size/threshold/drops) Conversations 2/9 (active/max active)
More on: Link1; Link2; Link3
CCNP Route 642-902 Questions/Answers - EIGRP
2013 51
Your network consists of a large hub-and-spoke Frame Relay network with a CIR of 56 kb/s for each
spoke.
Which statement about the selection of a dynamic protocol is true?
A. EIGRP would be appropriate if LMI type ANSI is NOT used.
B. EIGRP would be appropriate, because the Frame Relay spokes could be segmented into their own
areas.
C. EIGRP would be appropriate, because by default, queries are not propagated across the slow speed
Frame Relay links.
D. EIGRP would be appropriate, because you can manage how much bandwidth is consumed over the
Frame Relay interface.
Answer: D
By default, EIGRP uses up to 50 percent of the bandwidth declared on an interface or subinterface.
EIGRP uses the bandwidth of the link set by the bandwidth command, or the link’s default bandwidth if
none is configured, when calculating how much bandwidth to use.
You can adjust this percentage on an interface or subinterface with the ip bandwidth-percent eigrp
asnumber percent interface configuration command. The asnumber is the EIGRP autonomous system
number.
The percent parameter is the percentage of the configured bandwidth that EIGRP can use. You can set the
percentage to a value greater than 100, which might be useful if the bandwidth is configured artificially
low for routing policy reasons.
CCNP Route 642-902 Questions/Answers - EIGRP
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When an EIGRP topology change is detected, what is the correct order of events when there is a FS?
A. The neighbor adjacency is deleted.
The feasible route is used.
DUAL is notified.
Remove all topology entries learned from that neighbor.
B. DUAL is notified.
Remove all topology entries learned from that neighbor.
The neighbor adjacency is deleted.
Routes enter the Active state and the feasible route is used.
C. The neighbor adjacency is deleted.
Routes enter the Active state and the feasible route is used.
DUAL is notified.
Remove all topology entries learned from that neighbor.
D. DUAL is notified.
The neighbor adjacency is deleted.
Remove all topology entries learned from that neighbor.
The feasible route is used.
Answer: D
When a router loses a route, it looks at the topology table for an FS. If one is available, the route does not
go into an active state. Instead, the best FS is promoted as the successor and is installed in the routing
table.
The FS can be used immediately, without any recalculation. If there are no FSs, a route goes into active
state, and route computation occurs. Through this process, a new successor is determined (if there is one).
The amount of time it takes to recalculate the route affects the convergence time.
CCNP Route 642-902 Questions/Answers - EIGRP
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Refer to the exhibit. Why is the 140.140.0.0 network not used as the gateway of last resort even though it
is configured first?
R3#show run | include default-
ip default-network 140.140.0.0 ip default-network 130.130.0.0
R3#show ip route | begin Gateway
Gateway of last resort is 0.0.0.0 to network 130.130.0.0 116.0.0.0/8 is variably subnetted, 5 subnets, 3 masks
C 116.16.37.0/30 is directly connected, Serial1/0.2
C 116.16.32.0/30 is directly connected, Serial2/0.2 C 116.16.34.0/28 is directly connected, Serial1/0.1
C 116.16.35.0/28 is directly connected, Serial2/0.1
S 116.0.0.0/8 [1/0] via 116.16.34.0 * 140.140.0.0/32 is subnetted, 3 subnets
O 140.140.1.1 [110/65] via 116.16.34.4, 00:14:54, Serial1/0.1
O 140.140.3.1 [110/65] via 116.16.34.4, 00:14:54, Serial1/0.1 O 140.140.2.1 [110/65] via 116.16.34.4, 00:14:54, Serial1/0.1
* 130.130.0.0/16 is variably subnetted, 4 subnets, 2 masks
D* 130.130.0.0/16 is a summary, 00:30:04, Null0 C 130.130.1.0/24 is directly connected, Ethernet0/0
C 130.130.2.0/24 is directly connected, Ethernet0/1
C 130.130.3.0/24 is directly connected, Ethernet1/0 D 150.150.0.0/16 [90/679936] via 116.16.35.5, 00:02:58, Serial2/0.1
A. The last default-network statement will always be preferred.
B. A route to the 140.140.0.0 network does not exist in the routing table.
C. Default-network selection will always prefer the statement with the lowest IP address.
D. A router will load balance across multiple default-networks; repeatedly issuing the show ip route
command would show the gateway of last resort changing between the two networks.
Answer: B
The ip default-network command will only be in effect if network 140.140.0.0 exists in the router's
routing table.
More on: Link1; Link2
CCNP Route 642-902 Questions/Answers - EIGRP
2013 54
Refer to the exhibit. Why are the EIGRP neighbors for this router not learning the routes redistributed
from OSPF?
router eigrp 123
redistribute ospf 123
network 116.16.35.0 0.0.0.255
network 130.130.0.0
auto-summary
!
router ospf 123
log-adjacency-changes
network 116.16.34.0 0.0.0.255 area 0
neighbor 116.16.34.4
A. Redistribution must be enabled mutually (in both directions) to work correctly.
B. Auto-summary causes the OSPF routes redistributed into EIGRP to be summarized; thus the OSPF
network 116.16.34 is summarized to 116.34.0.0, which is already covered by the EIGRP protocol.
C. Default metrics are not configured under EIGRP.
D. Both routing protocols must have unique autonomous system numbers for redistribution to function
correctly.
Answer: C
To redistribute OSPF route into EIGRP 123 domain we have to use proper redistribution command,
which is:
Router(config)#router eigrp 123
Router(config- router)#redistribute ospf 123 metric Bandwidth_In_kbps
Delay_in_tens_of_microseconds Reliability Load MTU
Or an example:
Router(config- router)#redistribute ospf 123 metric 10000 100 255 1 1500
In our case metric is not configured properly in the redistribution command (there is not enough
parameters set).
CCNP Route 642-902 Questions/Answers - EIGRP
2013 55
Refer to the exhibit. You want to use all the routes in the EIGRP topology for IP load balancing. Which
two EIGRP subcommands would you use to accomplish this goal? (Choose two.)
R1#show ip eigrp topology | section 0.0.0.0
P 0.0.0/0 2 successors, FD is 2174976
via 212.50.185.125 (2174976/2169859), Ethernet0/0
via 212.50.185.126 (2174976/2169859), Ethernet0/0
via 212.50.185.65 (2178816/2172416), Ethernet1/0
via 212.50.185.66 (2178816/2172416), Ethernet1/0
via 212.50.185.33 (2180096/2172416), Ethernet1/0
via 212.50.185.34 (2180096/2172416), Ethernet1/0
R1#show up route 0.0.0.0
Routing entry for 0.0.0.0/0 supernet
Known via "eigrp 212", distance 170, metric 2174976, candidate default path, type external
Redistributing via eigrp 212
Last update from 212.50.185.126 on Ethernet0/0, 00:00:32 ago
Routing Descriptor Blocks:
* 212.50.185.126, from 212.50.185.26. 00:00:32 ago via Ethernet0/0
Route metric is 2174976, traffic share count is 1
Total delay is 20200 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 3/255, Hops 1
212.50.185.125, from 212.50.185.25. 00:00:32 ago via Ethernet0/0
Route metric is 2174976, traffic share count is 1
Total delay is 20200 microseconds, minimum bandwidth is 1544 Kbit
Reliability 255/255, minimum MTU 1500 bytes
Loading 3/255, Hops 1
A. traffic-share balanced
B. distance
C. maximum-paths
D. default-network
E. variance
Answer: C, E
Equal-cost load balancing is a router’s capability to distribute traffic over all the routers that have the
same metric for the destination address. All IP routing protocols on Cisco routers can perform equal-cost
load balancing. Load balancing increases the utilization of network segments, thus increasing effective
network bandwidth.
CCNP Route 642-902 Questions/Answers - EIGRP
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By default, the Cisco IOS balances between a maximum of four equal-cost paths for IP. Using the:
maximum-paths maximum-path
router configuration command, you can request that up to 16 equally good routes be kept in the routing
table. Set the maximum-path parameter to 1 to disable load balancing.
Note:
Load balancing is performed only on traffic that passes through the router, not traffic generated by the
router.
EIGRP can also balance traffic across multiple routes that have different metrics—this is called unequal-
cost load balancing. The degree to which EIGRP performs load balancing is controlled by the:
variance multiplier
router configuration command. The multiplier is a variance value, between 1 and 128, used for load
balancing. The default is 1, which means equal-cost load balancing. The multiplier defines the range of
metric values that are accepted for load balancing. Setting a variance value greater than 1 allows EIGRP
to install multiple loopfree routes with unequal cost in the routing table. EIGRP will always install
successors (the best routes) in the routing table. The variance allows feasible successors to also be
installed in the routing table.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 57
Refer to the exhibit. How would you confirm on R1 that load balancing is actually occurring on the
default-network (0.0.0.0)?
R1#show ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA exteranl type 2 E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per user static route o - ODR, P - periodic downloaded static route
Gateway of last resort is 212.50.185.126 to network 0.0.0.0
D 212.50.167.0/24 (90/160000) via 212.50.185.82, 00:05:55, Ethernet1/0
212.50.166.0/24 is variably subnetted, 4 subnets, 2 masks D 212.50.166.0/24 is a summary, 00:05:55, Null0
C 212.50.166.1/32 is directly connected, Loopback1
C 212.50.166.2/32 is directly connected, Loopback2 C 212.50.166.20/32 is directly connected, Loopback20
212.50.185.0/27 is subnetted, 3 subnets
C 212.50.185.64 is directly connected, Ethernet1/0 C 212.50.185.96 is directly connected, Ethernet0/0
C 212.50.185.32 is directly connected, Ethernet2/0
D*EX 0.0.0.0/0 (170/2174976) via 212.50.185.126, 00:05:55, Ethernet0/0 (170/2174976) via 212.50.185.125, 00:05:55, Ethernet0/0
A. Use ping and the show ip route command to confirm the timers for each default network resets to 0.
B. Load balancing does not occur over default networks; the second route will only be used for failover.
C. Use an extended ping along with repeated show ip route commands to confirm the gateway of last
resort address toggles back and forth.
D. Use the traceroute command to an address that is not explicitly in the routing table.
Answer: D
When you issue traceroute command with the destination IP address entry, more than one path will be
presented for each hop that traceroute calculates if there is load balancing through the paths.
More on: Link1
CCNP Route 642-902 Questions/Answers - EIGRP
2013 58
Refer to the exhibit. In a redundant hub-and-spoke deployment using EIGRP, what feature can be used to
ensure that routers C through F are not used as transit routers for data traveling from router B to network
10.1.1.0?
A. Use address summarization at routers C, D, E, and F.
B. Use the EIGRP Stub feature on routers C, D, E, and F.
C. Use passive-interface on the spoke links in routers A and B.
D. Change the administrative distance in routers A and B for routes learned from routers C, D, E, and F.
Answer: B
Limiting the scope of query propagation through the network (the query range), also known as query
scoping, helps reduce incidences of SIA (Stuck-in-Active). Keeping the query packets close to the source
reduces the chance that an isolated failure in another part of the network will restrict the convergence
(query/reply) process.
In hub-and-spoke network spoke (remote) routers will be configured as stub with commands:
Spoke(congfig)#router eigrp 1
Spoke(config)#eigrp stub
, if we use EIGRP AS 1.
CCNP Route 642-902 Questions/Answers - EIGRP
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Configuring spoke routers as stub we are reducing the bandwidth overloading and chance routes to
become SIA.
Note: There is another method for limiting the scope of query propagation through the network (the query
range) for our scenario. That is using route-summarization. If we configure route summarization on hub
router with command:
Hub(config-if)#ip summary-address eigrp ip_address_of_LAN netmask_for_LAN
on its outbound interfaces towards spoke routers, then summary route for LAN will be advertised.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 60
ACME Rocket Sleds is growing, and so is their network. They have determined that they can no longer
continue using static routes and must implement a dynamic routing protocol. They want to have data use
multiple paths to the destinations, even if the paths are not equal cost. Which routing protocol has the
ability to do this?
A. EIGRP
B. OSPF
C. RIPv1
D. RIPv2
E. BGP
F. IS-IS
Answer: A
EIGRP has ability to use two load balancing methods: equal costs load balancing and unequal costs load
balancing.
Equal-cost load balancing is a router’s capability to distribute traffic over all the routers that have the
same metric for the destination address. All IP routing protocols on Cisco routers can perform equal-cost
load balancing. Notice that the terminology is equal-cost even though the metric used in the routing
protocol may not be called cost (as is the case for EIGRP). Load balancing increases the utilization of
network segments, thus increasing effective network bandwidth. By default, the Cisco IOS balances
between a maximum of four equal-cost paths for IP. Using the maximum-paths maximum-path router
configuration command, you can request that up to 16 equally good routes be kept in the routing table. Set
the maximum-path parameter to 1 to disable load balancing.
When a packet is process-switched, load balancing over equal-cost paths occurs on a per-packet basis.
When packets are fast-switched, load balancing over equal-cost paths is on a per-destination basis.
EIGRP can also balance traffic across multiple routes that have different metrics—this is called unequal-
cost load balancing. The degree to which EIGRP performs load balancing is controlled by the variance
multiplier router configuration command. The multiplier is a variance value, between 1 and 128, used for
load balancing. The default is 1, which means equal-cost load balancing. The multiplier defines the range
of metric values that are accepted for load balancing. Setting a variance value greater than 1 allows
EIGRP to install multiple loopfree routes with unequal cost in the routing table. EIGRP will always install
successors (the best routes) in the routing table. The variance allows feasible successors to also be
installed in the routing table.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 61
Refer to the exhibit. Which statement about dynamic routing protocols for this network is true?
A. No dynamic interior routing protocol can summarize as shown.
B. Unless configured otherwise, EIGRP would automatically summarize the prefixes as shown in the
exhibit.
C. With this IP addressing scheme, EIGRP can be manually configured to summarize prefixes at the
specified summarization points.
D. The IP address design lends itself to OSPF. Each summarizing router would be an ABR, summarizing
to the next area in the address hierarchy.
Answer: C
Summarization minimizes the size of the routing table, which means less CPU and memory usage to
manage it and less bandwidth to transmit the information. Summarization also reduces the chance of
networks becoming SIA because it reduces the number of routers that see each query, so the chance of a
query encountering one of these issues is also reduced.
The Router(config-if)#ip summary-address eigrp eigrp-as-number network net-mask command is
configured on the outbound interfaces of routers to send summary route to neighboring router.
More on: Link1
CCNP Route 642-902 Questions/Answers - EIGRP
2013 62
After implementing EIGRP on your network, you issue the show ip eigrp traffic command on router C.
The following output is shown:
RouterC#show ip eigrp traffic
IP-EIGRP Traffic Statistics for process 1
Hellos sent/received: 481/444 Updates sent/received: 41/32
Queries sent/received: 5/1
Replies sent/received: 1/4 Acks sent/received: 21/25
Input queue high water mark 2, 0 drops
SIA-Queries sent/received: 0/0 SIA-Replies sent/received: 0/0
Approximately 25 minutes later, you issue the same command again. The following output is shown:
RouterC#show ip eigrp traffic
IP-EIGRP Traffic Statistics for process 1 Hellos sent/received: 1057/1020
Updates sent/received: 41/32
Queries sent/received: 5/1 Replies sent/received: 1/4
Acks sent/received: 21/25
Input queue high water mark 2, 0 drops SIA-Queries sent/received: 0/0
SIA-Replies sent/received: 0/0
Approximately 25 minutes later, you issue the same command a third time. The following output is
shown:
RouterC#show ip eigrp traffic
IP-EIGRP Traffic Statistics for process 1
Hellos sent/received: 1754/1717
Updates sent/received: 41/32 Queries sent/received: 5/1
Replies sent/received: 1/4
Acks sent/received: 21/25 Input queue high water mark 2, 0 drops
SIA-Queries sent/received: 0/0
SIA-Replies sent/received: 0/0
What can you conclude about this network?
A. The network has been stable for at least the last 45 minutes.
B. There is a flapping link or interface, and router C knows an alternate path to the network.
C. There is a flapping link or interface, and router A does not know an alternate path to the network.
CCNP Route 642-902 Questions/Answers - EIGRP
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D. EIGRP is not working correctly on router C.
E. There is not enough information to make a determination.
Answer: A
The show ip eigrp traffic command summarizes the number of hello packets router receives and
sends. show ip eigrp traffic command show how many updates, queries, replies, and acknowledges router
uses to ensure that EIGRP is running correctly and there are exchanges with adjacent EIGRP routers.
If we look in the query statement in show ip eigrp traffic command, we can see that 5 queries are sent and
just 1 received. That means there is no Feasible Successor for some route in the routing table, for which
Successor is not available any more. Router will start sending queries to find alternative route to the
destination network, for which this route exist in topology table as Active route.
In other words, when a route goes active and queries are initiated, the only way this route can come out of
the active state and transition to passive state is by receiving a reply for every generated query. If the
router does not receive a reply to all the outstanding queries within 3 minutes (the default time), the route
goes to the SIA (Stack-In-Active) state.
When a route goes to SIA state, the router resets the neighbor relationships for the neighbors that failed to
reply. This causes the router to recompute all routes known through that neighbor and to readvertise all
the routes it knows about to that neighbor.
Important Note: In our case because there is no changes in queries sent/received values for more than 50
minutes, we may say that SIA timer is changed with following command to match higher value than 3
minutes (more than 50 minutes).
You can change the active-state time limit from its default of 3 minutes using the:
timers active-time [timelimit|disabled]
router configuration command. The time-limit is in minutes.
Until all 5 queries are not received route will be Stuck-In-Active, but network topology is stable and there
is no network changes, except that active route is unavailable for present router.
More on: Link1
CCNP Route 642-902 Questions/Answers - EIGRP
2013 64
Refer to the exhibit. Your company is planning to implement load balancing for traffic between hosts on
the 172.16.10.0/24 and 172.16.20.0/24 networks. You have been asked to review the implementation plan
for this project. Which statement about the plan is true?
Implementation Plan
1. Configure variance on R1 and R4.
2. Use traceroute to validate load balancing has been activated.
3. Document configuration changes.
A. It is complete as written.
B. It should include a task to configure EIGRP multipath equal to 2 on R1 and R4.
C. It should include a task to implement OSPF because it handles unequal cost load balancing most
efficiently using variance.
D. It should include a task that establishes a baseline before and after the configuration has been changed.
Answer: D
Here from router R1 we have two links to the destination network 172.16.20.0/24 (R1-R2-R4 and R1-R3-
R4). Because we have different bandwidths on both links, we will have different metrics for both links.
This means (if all is configured by default) that just one link will be placed in the routing table of R1.
We have to make implementation plan how to make unequal cost path load balancing and to put both
routes in the routing table (one as Successor and other as Feasible). To accomplish this we have to set
variance value higher than 1 (if we have value 1 we will have equal cost path load balancing), that will
make this route to be feasible.
Because implementation plan needs to include instruction how to accomplish this, we have to take care of
the present situation and future changes in the network. These changes must be established as document,
to be able to do rollback plan if is necessary.
CCNP Route 642-902 Questions/Answers - EIGRP
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Note: Every routing protocol supports equal cost path load balancing. In addition to that, IGRP and
EIGRP also support unequal cost path load balancing.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 66
Refer to the exhibit. Your company is planning to implement load balancing for traffic between host on
the 172.16.10.0/24 and 172.16.20.0/24 networks. You have been asked to review the implementation plan
for this project. Which statement about the plan is true?
Implementation Plan:
1. Enable a traffic throughput baseline.
2. Configure variance on R1 and R4.
3. Use traceroute to validate load balancing has been activated.
4. Establish a new traffic throughput baseline.
5. Compare the new and old baselines and verify that load balancing
is implemented as desired.
A. It is complete as written.
B. It should include a task to configure multipath to equal a value of 2 on R1 and R4.
C. It should use a ping instead of a traceroute to validate that load balancing has been activated.
D. It should contain a task that documents the changes made to the configurations.
Answer: D
Here from router R1 we have two links to the destination network 172.16.20.0/24 (R1-R2-R4 and R1-R3-
R4). Because we have different bandwidths on both links, we will have different metrics for both links.
This means (if all is configured by default) that just one link will be placed in the routing table of R1.
We have to make implementation plan how to make unequal cost path load balancing and to put both
routes in the routing table (one as Successor and other as Feasible). To accomplish this we have to set
variance value higher than 1 (if we have value 1 we will have equal cost path load balancing), that will
make this route to be feasible.
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Because implementation plan needs to include instruction how to accomplish this, we have to take care of
the present situation and future changes in the network. These changes must be established as document,
to be able to do rollback plan if is necessary.
Note: Every routing protocol supports equal cost path load balancing. In addition to that, IGRP and
EIGRP also support unequal cost path load balancing.
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Which three statements are true about EIGRP operation? (Choose three.)
A. When summarization is configured, the router will also create a route to null 0.
B. The summary route remains in the route table, even if there are no more specific routes to the network.
C. Summarization is configured on a per-interface level.
D. The maximum metric for the specific routes is used as the metric for the summary route.
E. Automatic summarization across major network boundaries is enabled by default.
Answer: A, C, E
- On router that runs EIGRP, auto-summarization creates summary route pointed to Null0 interface,
which is advertised to the neighboring routers. This way of routing is used to prevent maintenance of
large routing tables in the network.
- If you want to send summarized routes to the neighboring router you have to use manual summarization.
Example of summarizing routes into network 10.1.1.0/24 through outbound interface fa0/1:
Router(config-if)#int fa0/1
Router(config-if)#ip summary-address eigrp 1 10.1.1.0 255.255.255.0
- Administrative distance of summary route is 5.
- Auto-summary for EIGRP is enabled by default on a router (on newer Cisco IOS versions it is disabled
by default, so you don’t need to use no-auto summary).
More on: Link1; Link2
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Which two statements about the EIGRP DUAL process are correct? (Choose two.)
A. An EIGRP route will go active if there are no successors or feasible successors in the EIGRP topology
table.
B. An EIGRP route will go passive if there are no successors in the EIGRP topology table.
C. DUAL will trigger an EIGRP query process while placing the flapping routes in the holddown state.
D. A feasible successor in the EIGRP topology table can become the successor only after all the query
requests have been replied to.
E. The stuck in active state is caused when the wait for the query replies have timed out.
F. EIGRP queries are sent during the loading state in the EIGRP neighbor establishment process.
Answer: A, E
- Passive route to destination network is operational route that is placed in the topology table.
- When a router loses a route, it looks at the topology table for an FS. If one is available, the route does
not go into an active state. Instead, the best FS is promoted as the successor and is installed in the routing
table. The FS can be used immediately, without any recalculation. If there are no FSs, a route goes into
active state, and route computation occurs. Through this process, a new successor is determined (if there
is one). The amount of time it takes to recalculate the route affects the convergence time.
- Because of the reliable multicast approach used by EIGRP when searching for an alternative to a lost
route, it is imperative that a reply be received for each query generated in the network. In other words,
when a route goes active and queries are initiated, the only way this route can come out of the active state
and transition to passive state is by receiving a reply for every generated query. If the router does not
receive a reply to all the outstanding queries within 3 minutes (the default time), the route goes to the SIA
(Stack-In-Active) state.
When a route goes to SIA state, the router resets the neighbor relationships for the neighbors that failed to
reply. This causes the router to recompute all routes known through that neighbor and to readvertise all
the routes it knows about to that neighbor.
More on: Link1
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What are three key concepts that apply when configuring the EIGRP stub routing feature in a hub and
spoke network? (Choose three.)
A. A hub router prevents routes from being advertised to the remote router.
B. Only remote routers are configured as stubs.
C. Stub routers are not queried for routes.
D. Spoke routers connected to hub routers answer the route queries for the stub router.
E. A stub router should have only EIGRP hub routers as neighbors.
F. EIGRP stub routing should be used on hub routers only.
Answer: B, C, E
Hub-and-spoke network topologies commonly use stub routing. In this topology, the remote router
forwards all traffic that is not local to a hub router, so the remote router does not need to retain a complete
routing table. Generally, the hub router needs to send only a default route to the remote routers.
Only the remote routers are configured as stubs. The stub feature does not prevent routes from being
advertised to the remote router.
A stub router indicates in the hello packet to all neighboring routers its status as a stub router. Any router
that receives a packet informing it of its neighbor’s stub status does not query the stub router for any
routes.
Therefore, a router that has a stub peer does not query that peer.
Thus, it is important to note that stub routers are not queried. Instead, hub routers connected to the stub
router answer the query on behalf of the stub router.
Caution: EIGRP stub routing should be used on stub routers only. A stub router is defined as a router
connected to the network core or hub layer, and through which core transit traffic should not flow. A stub
router should have only hub routers for EIGRP neighbors. Ignoring this restriction causes undesirable
behavior.
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Which command will display EIGRP packets sent and received, as well as statistics on hello packets,
updates, queries, replies, and acknowledgments? (Choose one)
A. debug eigrp packets
B. show ip eigrp traffic
C. debug ip eigrp
D. show ip eigrp interfaces
Answer: B
The show ip eigrp traffic command displays the number of Enhanced IGRP (EIGRP) packets sent and
received.
Example:
The following is sample output from the show ip eigrp traffic command:
Router# show ip eigrp traffic
IP-EIGRP Traffic Statistics for process 77 Hellos sent/received: 218/205
Updates sent/received: 7/23
Queries sent/received: 2/0 Replies sent/received: 0/2
Acks sent/received: 21/14
More on: Link1
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Based on the exhibited output, which three statements are true? (Choose three.)
R1#show ip eigrp topology
IP-EIGRP Topology Table for process 200
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - Reply Status
P 192.168.1.64/28 1 successors, FD is 281600 via Connected, Ethernet0 P 192.168.1.32/28 2 successors, FD is 40512000 via Connected, Serial1
P 192.168.1.48/28 1 successors, FD is 40537600
via 192.168.1.66, (40537600/40512000), Ethernet0 via 192.168.1.17, (41024000/40512000), Serial0
via 192.168.1.33, (41024000/40512000), Serial1
P 192.168.1.16/28 1 successors, FD is 40512000 via Connected, Serial0
A. R1 is in AS 200.
B. R1 will load balance between three paths to reach the 192.168.1.48/28 prefix because all three paths
have the same advertised distance (AD) of 40512000.
C. The best path for R1 to reach the 192.168.1.48/28 prefix is via 192.168.1.66.
D. 40512000 is the advertised distance (AD) via 192.168.1.66 to reach the 192.168.1.48/28 prefix.
E. All the routes are in the passive mode because these routes are in the hold-down state.
F. All the routes are in the passive mode because R1 is in the query process for those routes.
Answer: A, C, D
It can be determined that AS 200 is used, from the fact that the EIGRP process ID is labeled as 200. The
best path to reach the network 192.168.1.48/28 is the first one displayed in the routing table (noted that
there is just 1 suceessor).
This can be further demonstrated by the fact that the metric (feasible distance value) is less than the
alternative route, via Serial 0 and alternative route through Serial1.
Finally, the AD can be found by viewing the second number within the parentheses, which in this case is
40512000.
Statement from topology table:
via 192.168.1.66, (40537600/40512000), Ethernet0
is same as written statement below:
(via 192.168.1.66, (FD/AD), Ethernet0
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Refer to the exhibit. EIGRP is configured with the default configuration on all routers.
Autosummarization is enabled on routers R2 and R3, but it is disabled on router R1. Which two EIGRP
routes will be seen in the routing table of router R3? (Choose two.)
R1#show running config
! router eigrp 4
network 10.0.0.0
network 172.16.0.0 no auto-summary
!
A. 10.0.0.0/8
B. 10.10.0.0/16
C. 10.10.10.0/24
D. 172.16.0.0/16
E. 172.16.0.0/24
F. 172.16.10.0/24
Answer: C, D
Because on router R1 is disabled autosummarization, this router will advertise network 10.10.10.0/24 to
the neighboring router R2, which will advertise it to the router R3.
Router R2 got enabled autosummarization, so it will advertise summarized route for network
172.16.10.0/24 (this route will be 172.16.0.0/16) to router R3.
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Refer to the exhibit. EIGRP has been configured on routers R1 and R2. However, R1 does not show R2
as a neighbor and does not accept routing updates from R2. What could be the cause of the problem?
hostname R1
! interface Ethernet0
ip address 10.1.1.1 255.255.255.0
! router eigrp 4
network 10.0.0.0
hostname R2
! interface Ethernet0
ip address 10.1.2.2 255.255.255.0
ip address 10.1.1.2 255.255.255.0 secondary !
router eigrp 4
network 10.0.0.0
R1#show ip eigrp neighbor
IP-EIGRP neighbor for process
01:20:54: IP=EIGRP: Neighbor 10.1.2.2 not on common subnet for Ethernet0 (10.1.) 01:21:08: IP=EIGRP: Neighbor 10.1.2.2 not on common subnet for Ethernet0 (10.1.)
R2#show ip eigrp neighbor
IP-EIGRP neighbors for process 4
H Address Interface Hold Uptime SRTT RTO Q Seq Type (sec) (ms) Cnt Num
O 10.1.1.1 Et0 12 00:00:35 1 5000 1 0
A. The no auto-summary command has not been issued under the EIGRP process on both routers.
B. Interface E0 on router R1 has not been configured with a secondary IP address of 10.1.2.1/24.
C. EIGRP cannot exchange routing updates with a neighbor's router interface that is configured with two
IP addresses.
D. EIGRP cannot form neighbor relationship and exchange routing updates with a secondary address.
Answer: D
If any router on a network segment uses a secondary address, all other routers on that same segment must
also use a secondary address from the same network or subnet.
More on: Link1
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Refer to the exhibit. EIGRP had converged in AS 1 when the link between router R1 and R2 went down.
The console on router R2 generated the following messages:
*Mar 20 12:12:06: %DUAL-5-NBRCHANGE: IP-EIGRP 1: Neighbor 10.1.4.3 (Serial0) is down:
stuck in active *Mar 20 12:15:23: %DUAL-3-SIA: Route 10.1.1.0/24 stuck-in-active state in IP-EIGRP 1.
Cleaning up
The network administrator issued the show ip eigrp topology active command on R2 to check the status of
the EIGRP network. Which statement best describes the reason for the error messages?
R2#show ip eigrp topology active
IP-EIGRP Topology Table for process 1
Codes: P - Passive, A - Active, U - update, Q - Query, R - Relay, r - Relay status
A 10.1.1.0 255.255.255.0, 1 successors, FD is 2733056 1 replies, active 0:00:38, query-orgin: Multiple Orgins
via 10.1.3.3(infinity/infinity), r, Serial0, semp 1232 via 10.1.5.5(infinity/infinity), Serial1, semp 1227
A. Incorrect bandwidth configuration on router R3 prevents R2 from establishing neighbor adjacency.
B. Incorrect bandwidth configuration on router R5 prevents R2 from establishing neighbor adjacency.
C. Router R3 did not reply to the query about network 10.1.1.0/24 sent by router R2.
D. Router R5 did not reply to the query about network 10.1.1.0/24 sent by router R2.
Answer: C
Unfortunately, this question is the hardest part of troubleshooting SIAs. Because the SIA timer is a little
over 3 minutes by default, it is necessary to track down an unresponsive router within this time period. To
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do so, make sure that you have a network topology diagram that includes all routers in the network along
with their IP addresses.
You can determine which routes are active on a router by issuing the show ip eigrp topology
active command. It is normal for this command to list some active routes. The existence of an active route
does not, by itself, indicate a problem; pay particular attention to routes that have been active for longer
than one minute.
The output above tells you that EIGRP has been active for 10.1.1.0/24 for 38 seconds, has queried two
neighbors, and is still waiting on a reply from 10.1.3.3. The lowercase r indicates that the router is waiting
for a reply to a query. A capital R indicates that it received a reply from this neighbor.
More on: Link1
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Which EIGRP packet statement is true?
A. On high-speed links, hello packets are broadcast every 5 seconds for neighbor discovery.
B. On low-speed links, hello packets are broadcast every 15 seconds for neighbor discovery.
C. Reply packets are multicast to IP address 224.0.0.10 using RTP.
D. Update packets route reliable change information only to the affected routers.
E. Reply packets are used to send routing updates.
Answer: D
EIGRP uses the following five types of packets:
- Hello - Hello packets are used for neighbor discovery. They are sent as multicasts and do not require an
acknowledgment. (They carry an acknowledgment number of 0.)
- Update - Update packets contain route change information. An update is sent to communicate the routes
that a particular router has used to converge. An update is sent only to affected routers. Update packets
are sent as multicasts when a new route is discovered, and when convergence is complete (in other words,
when a route becomes passive). To synchronize topology tables, update packets are sent as unicasts to
neighbors during their EIGRP startup sequence. Update packets are sent reliably.
- Query - When a router is performing route computation and does not have an FS, it sends a query packet
to its neighbors, asking whether they have a successor to the destination. Queries are normally multicast
but can be retransmitted as unicast packets in certain cases. They are sent reliably.
- Reply - A reply packet is sent in response to a query packet. Replies are unicast to the originator of the
query and are sent reliably. A router must reply to all queries.
- ACK - The ACK is used to acknowledge updates, queries, and replies. ACK packets are unicast hello
packets and contain a nonzero acknowledgment number. (Note that hello and ACK packets do not require
acknowledgment.)
Through the hello protocol, an EIGRP router dynamically discovers other EIGRP routers directly
connected to it. The router sends hello packets out of interfaces configured for EIGRP using the EIGRP
multicast address 224.0.0.10. When an EIGRP router receives a hello packet from a router belonging to
the same autonomous system, it establishes a neighbor relationship (adjacency).
The time interval of hello packets varies depending on the medium. By default, hello packets are sent
every 60 seconds on T1 or slower NBMA interfaces and every 5 seconds on other serial interfaces and on
LANs.
More on: Link1
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Refer to the exhibit. EIGRP has been configured on all routers in the network. The command metric
weights 0 0 1 0 0 has been added to the EIGRP process so that only the delay metric is used in the path
calculations. Which router will R1 select as the successor and feasible successor for Network A?
A. R4 becomes the successor for Network A and will be placed in the routing table. R2 becomes the
feasible successor for Network A.
B. R4 becomes the successor for Network A and will be included in the routing table. No feasible
successor will be selected as the advertised distance from R2 is higher than the feasible distance.
C. R2 becomes the successor and will be placed in the routing table. R4 becomes the feasible successor
for Network A.
D. R2 becomes the successor and will be placed in the routing table. No feasible successor will be
selected as the reported distance from R4 is lower than the feasible distance.
Answer: B
EIGRP metric can be calculated with formula:
There are given following K values:
0 0 1 0 0
So, metric is calculated with:
Delay is calculated as sum of delays of any links between the routers through the routing path.
Metric (FD) for path R1-R2-R3-Sw-R5:
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Advertised Distance (AD) for path R1-R2-R3-Sw-R5:
Metric (FD) for path R1-R4-Sw-R5:
Advertised Distance (AD) for path R1-R4-Sw-R5:
Successor is router with lower metric to the destinatioion network. In our case that is router R4 (got lower
metric – 5120<7680 between two present routing paths).
Feasability condition for path R1-R2-R3-Sw-R5:
Must be satisfied: AD(Path_ R1-R2-R3-Sw-R5)< FD(Path_ R1-R4-Sw-R5) (*)
e.g. 6400<5120 - (it is not satisfied)
We can see that (*) is not satisfied, so we don’t have FS to the destination network.
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You are a network technician responsible for company network maintenance and upgrade. What must be
done on router PGA in order to make EIGRP work effectively in a Frame Relay multipoint environment?
A. Issue the command bandwidth 56 on the physical interface.
B. Issue the command bandwidth 56 on each subinterface.
C. Issue the command bandwidth 224 on each subinterface.
D. Issue the command bandwidth 224 on the physical interface.
Answer: D
When configuring multipoint interfaces, configure bandwidth to represent minimum CIR times the
number of circuits. In our case we have:
minimum CIR * the number of circuits=56*4=224 kbps
So S0 needs to be configured with command:
PGA(config)#int s0
PGA(config-if)#bandwidth 224
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Which three descriptions are correct based on the exhibited output? (Choose three.)
PG-R1#show ip route
Gateway po last resort is 10.1.1.2 to network 0.0.0.0
C 1.0.0.0/8 is directly connected, Lookback0 172.17.0.0/24 is subnetted, 1 subnet
D 172.17.1.0 [90/25632000] via 10.1.1.2, 00:05:20, Serial0/0
172.16.0.0/24 is subnetted, 1 subnet D 172.16.1.0 [90/23072000] via 10.1.1.2, 00:05:20, Serial0/0
[90/20640000] via 10.1.1.3, 00:00:13, Serial0/0
D 172.19.0.0 [90/391248640] via 10.1.1.3, 00:05:20, Serial0/0 D 172.22.0.0 [90/20640000] via 10.1.1.3, 00:05:21, Serial0/0
D EX 172.25.0.0 [170/32032000] via 10.1.1.2, 00:00:10, Serial0/0
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks D 10.2.0.0/16 is a summary, 00:16:18, Null0
C 10.2.1.0/24 is directly connected, FastEthernet0/0
C 10.1.1.0/24 is directly connected, Serial0/0 D*EX 0.0.0.0 [170/20514560] via 10.1.1.2, 00:00:11, Serial0/0
A. PG-R1 is configured with the variance command.
B. The route to 10.2.0.0/16 was redistributed into EIGRP.
C. A default route has been redistributed into the EIGRP autonomous system.
D. PG-R1 is configured with the ip summary-address command.
Answer: A, C, D
1) We can see that:
PG-R1#show ip route
Gateway po last resort is 10.1.1.2 to network 0.0.0.0
C 1.0.0.0/8 is directly connected, Lookback0
172.17.0.0/24 is subnetted, 1 subnet
D 172.17.1.0 [90/25632000] via 10.1.1.2, 00:05:20, Serial0/0 172.16.0.0/24 is subnetted, 1 subnet
D 172.16.1.0 [90/23072000] via 10.1.1.2, 00:05:20, Serial0/0
[90/20640000] via 10.1.1.3, 00:00:13, Serial0/0 D 172.19.0.0 [90/391248640] via 10.1.1.3, 00:05:20, Serial0/0
D 172.22.0.0 [90/20640000] via 10.1.1.3, 00:05:21, Serial0/0
D EX 172.25.0.0 [170/32032000] via 10.1.1.2, 00:00:10, Serial0/0 10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
D 10.2.0.0/16 is a summary, 00:16:18, Null0
C 10.2.1.0/24 is directly connected, FastEthernet0/0 C 10.1.1.0/24 is directly connected, Serial0/0
D*EX 0.0.0.0 [170/20514560] via 10.1.1.2, 00:00:11, Serial0/0
In the routing table we have two routes (one with metric 23072000 and other with metric 20640000.They
don’t have same metric. Second route to be able to be in the routing table, must be non-equal cost path
load balancing configured on router (variance is with value higher than 1).
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2) We can see that there is route (D*EX 0.0.0.0) in the routing table:
PG-R1#show ip route
Gateway po last resort is 10.1.1.2 to network 0.0.0.0
C 1.0.0.0/8 is directly connected, Lookback0
172.17.0.0/24 is subnetted, 1 subnet
D 172.17.1.0 [90/25632000] via 10.1.1.2, 00:05:20, Serial0/0 172.16.0.0/24 is subnetted, 1 subnet
D 172.16.1.0 [90/23072000] via 10.1.1.2, 00:05:20, Serial0/0
[90/20640000] via 10.1.1.3, 00:00:13, Serial0/0 D 172.19.0.0 [90/391248640] via 10.1.1.3, 00:05:20, Serial0/0
D 172.22.0.0 [90/20640000] via 10.1.1.3, 00:05:21, Serial0/0
D EX 172.25.0.0 [170/32032000] via 10.1.1.2, 00:00:10, Serial0/0 10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
D 10.2.0.0/16 is a summary, 00:16:18, Null0
C 10.2.1.0/24 is directly connected, FastEthernet0/0 C 10.1.1.0/24 is directly connected, Serial0/0
D*EX 0.0.0.0 [170/20514560] via 10.1.1.2, 00:00:11, Serial0/0
that is EIGRP redistributed external default route, from other routing domain.
3) We can see that router PG-R1 have got summary route that is manually configured with command ip
summary-address.
PG-R1#show ip route
Gateway po last resort is 10.1.1.2 to network 0.0.0.0
C 1.0.0.0/8 is directly connected, Lookback0 172.17.0.0/24 is subnetted, 1 subnet
D 172.17.1.0 [90/25632000] via 10.1.1.2, 00:05:20, Serial0/0
172.16.0.0/24 is subnetted, 1 subnet D 172.16.1.0 [90/23072000] via 10.1.1.2, 00:05:20, Serial0/0
[90/20640000] via 10.1.1.3, 00:00:13, Serial0/0
D 172.19.0.0 [90/391248640] via 10.1.1.3, 00:05:20, Serial0/0 D 172.22.0.0 [90/20640000] via 10.1.1.3, 00:05:21, Serial0/0
D EX 172.25.0.0 [170/32032000] via 10.1.1.2, 00:00:10, Serial0/0
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks D 10.2.0.0/16 is a summary, 00:16:18, Null0
C 10.2.1.0/24 is directly connected, FastEthernet0/0
C 10.1.1.0/24 is directly connected, Serial0/0
D*EX 0.0.0.0 [170/20514560] via 10.1.1.2, 00:00:11, Serial0/0
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After DUAL calculations, a router has identified a successor route, but no routes have qualified as a
feasible successor. In the event that the current successor goes down, what process will EIGRP use in the
selection of a new successor?
A. EIGRP will find the interface with the lowest MAC address.
B. The route will transition to the active state.
C. The route will transition to the passive state.
D. EIGRP will automatically use the route with the lowest feasible distance (FD).
E. EIGRP will automatically use the route with the lowest advertised distance (AD).
Answer: B
In the topology table there are successor and feasible successor routes. Routes that can be used for routing
are notated as routes in passive state (noted with P at the beginning of statement in topology table)..
Routes that can’t be used for routing are notated as routes in active state (noted with A at the beginning of
statement in topology table).
When a router loses a route, it looks at the topology table for an FS. If one is available, the route does not
go into an active state. Instead, the best FS is promoted as the successor and is installed in the routing
table. The FS can be used immediately, without any recalculation. If there are no FSs, a route goes into
active state, and route computation occurs. Through this process, a new successor is determined (if there
is one). The amount of time it takes to recalculate the route affects the convergence time.
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Which three statements about the EIGRP routing protocol are true? (Choose three)
A. EIGRP sends periodic hello packets to the multicast IP address 224.0.0.9
B. EIGRP sends periodic hello packets to the multicast IP address 224.0.0.10
C. EIGRP supports five generic packet types. Including hello, update, query, reply, and ACK packets
D. EIGRP supports five generic packet types. Including hello, database description (DBD), Link-state
request (LSR), link-state update (LSU), and LSAck
E. EIGRP will form a neighbor relationship with another peer even when their K values are mismatched.
F. EIGRP will not form a neighbor relationship with another peer even when their K values are
mismatched.
Answer: B, C, F
1) EIGRP uses the following five types of packets:
- Hello - Hello packets are used for neighbor discovery. They are sent as multicasts and do not require an
acknowledgment. (They carry an acknowledgment number of 0.)
- Update - Update packets contain route change information. An update is sent to communicate the routes
that a particular router has used to converge. An update is sent only to affected routers. Update packets
are sent as multicasts when a new route is discovered, and when convergence is complete (in other words,
when a route becomes passive). To synchronize topology tables, update packets are sent as unicasts to
neighbors during their EIGRP startup sequence. Update packets are sent reliably.
- Query - When a router is performing route computation and does not have an FS, it sends a query
packet to its neighbors, asking whether they have a successor to the destination. Queries are normally
multicast but can be retransmitted as unicast packets in certain cases. They are sent reliably.
- Reply - A reply packet is sent in response to a query packet. Replies are unicast to the originator of the
query and are sent reliably. A router must reply to all queries.
- ACK - The ACK is used to acknowledge updates, queries, and replies. ACK packets are unicast hello
packets and contain a nonzero acknowledgment number. (Note that hello and ACK packets do not require
acknowledgment.)
2) Through the hello protocol, an EIGRP router dynamically discovers other EIGRP routers directly
connected to it. The router sends hello packets out of interfaces configured for EIGRP using the EIGRP
multicast address 224.0.0.10. When an EIGRP router receives a hello packet from a router belonging to
the same autonomous system, it establishes a neighbor relationship (adjacency). The time interval of hello
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packets varies depending on the medium. By default, hello packets are sent every 60 seconds on T1 or
slower NBMA interfaces and every 5 seconds on other serial interfaces and on LANs.
3) Two routers can become EIGRP neighbors even though the hello and hold time values do not match.
This means that the hello interval and hold-time values can be set independently on different routers.
EIGRP will not build peer relationships over secondary addresses because all EIGRP traffic uses the
interface’s primary address. To form an EIGRP adjacency, all neighbors use their primary address as the
source IP address of their EIGRP packets. Adjacency between EIGRP routers takes place if the primary
address of each neighbor is part of the same IP subnet.
In addition, peer relationships are not formed if the neighbor resides in a different EIGRP autonomous
system or if the metric-calculation mechanism constants (the K values) are misaligned on that link.
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EIGRP has been configured to operate over Frame Relay multipoint connections. What should the
bandwidth command be set to?
A. the CIR rate of the lowest speed connection multiplied by the number of circuits
B. the CIR rate of the lowest speed connection
C. the CIR rate of the highest speed connection
D. the sum of all the CIRs divided by the number of connections
Answer: A
If the multipoint network has different speeds allocated to the VCs, take the lowest CIR and simply
multiply it by the number of circuits. This is because in Frame-relay all neighbors share the bandwidth
equally, regardless of the actual CIR of each individual PVC, so we have to get the lowest speed CIR rate
and multiply it by the number of circuits. This result will be applied on the physical interface (where
subinterfaces are coinfigured on it).
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Refer to the exhibit. EIGRP is configured on all routes in the network. On a basis of the show ip eigrp
topology output provided, what conclusion can be derived?
R1#show ip eigrp topology
<output omitted>
P 10.1.2.0/24 1 seccussors, FD is 281600 via Connected, FastEthernet0/0 A 10.6.1.0/24 0 seccussors, FD is 3385160704, Q 1 replies, active 00:00:41, query-origin: Local orgin
Remaining replies:
via 10.1.2.1, r. FastEthernet0/0
A. Router R1 can send traffic destined for network 10.6.1.0/24 out of interface FastEthernet0/0
B. Router R1 is waiting for a reply from the neighbor 10.1.2.1 to the hello message sent out before it
declares the neighbor unreachable
C. Router R1 is waiting for a reply from the neighbor 10.1.2.1 to the hello message sent out inquiring for
a second successor to network 10.6.1.0/24
D. Router R1 is waiting for a reply from the neighbor 10.1.2.1 in response to the query sent about
network 10.6.1.0/24
Answer: D
The "show ip eigrp topology" command lists all routes that EIGRP is aware of and shows whether EIGRP
is actively processing information on that route.
We can see that route to network 10.6.1.0/24 is indicated as active route (A) and that R1 waits for queries
replies (indicated with r).
R1#show ip eigrp topology
<output omitted>
P 10.1.2.0/24 1 seccussors, FD is 281600 via Connected, FastEthernet0/0 A 10.6.1.0/24 0 seccussors, FD is 3385160704, Q 1 replies, active 00:00:41, query-origin: Local orgin
Remaining replies:
via 10.1.2.1, r. FastEthernet0/0
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Which three route filtering statements are true? (Choose three)
A. After the router rip and passive-interface s0/0 commands have been issued, the s0/0 interface will not
send any RIP updates, but will receive routing updates on that interface.
B. After the router eigrp 10 and passive-interface s0/0 commands have been issued, the s0/0 interface
will not send any EIGRP updates, but will receive routing updates on that interface
C. After the router ospf 10 and passive-interface s0/0 commands have been issued, the s0/0 interface will
not send any OSPF updates, but will receive routing updates on that interface
D. When you use the passive-interface command with RIPv2, multicasts are sent out the specified
interface
E. When you use the passive-interface command with EIGRP, hello messages are not sent out the
specified interface
F. When you use the passive-interface command with OSPF, hello messages are not sent out the
specified interface
Answer: A, E, F
passive-interface command is used in all routing protocols to disable sending updates out from a specific
interface. However the command behavior varies from one protocol to another:
- In RIP, this command will not allow sending multicast updates via a specific interface but will allow
listening to incoming updates from other RIP speaking neighbors. This means that the router will still be
able to receive updates on that passive interface and use them in its routing table.
- In EIGRP and OSPF the passive-interface command stops sending outgoing hello packets, hence the
router can not form any neighbor relationship via the passive interface. This behavior stops both outgoing
and incoming routing updates.
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Which three statements are true about EIGRP route summarization? (Choose three.)
A. Manual route summarization is configured in router configuration mode when the router is configured
for EIGRP routing.
B. Manual route summarization is configured on the interface.
C. When manual summarization is configured, the summary route will use the metric of the largest
specific metric of the summary routes.
D. The ip summary-address eigrp command generates a default route with an administrative distance of
90.
E. The ip summary-address eigrp command generates a default route with an administrative distance of
5.
F. When manual summarization is configured, the router immediately creates a route that points to Null0
interface.
Answer: B, E, F
The purpose of route summarization is small routing tables, smaller updates. On major network
boundaries, subnetworks are summarized to a single classful network and automatic route summarization
is enabled by default. Manual route summarization can be configured on per interface basis. When
summarization is configured on an interface, the router immediately creates a route pointing to Null0.
Route summarization works in conjunction with the ip summary-address eigrp interface configuration
command, in which additional summarization can be performed. If automatic summarization is in effect,
there usually is no need to configure network level summaries using the ip summary-address eigrp
command. You can configure a summary aggregate address for a specified interface. Administrative
distance of manually configured summary route in EIGRP is 5.
More on: Link1; Link2
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Refer to the exhibit. Routers R1 and R2 are running EIGRP and have converged. On the basis of the
information that is presented, which statement is true?
hostname R1 !
router eigrp 4 network 172.16.8.0 0.0.0.255
network 172.16.135.0 0.0.0.255
passive-interface serial0/0 distribute-list 20 out serial0/0
!
access-list 20 permit 172.16.8.0 0.0.0.255 access-list 20 deny 0.0.0.0
access-list 20 permit any
A. All outgoing routing updates from router R1 to router R2 will be suppressed, but the inbound updates
will continue to be received.
B. All incoming routing updates from R2 will be suppressed, but the outgoing updates will continue to be
sent.
C. Both outgoing and incoming routing updates on R1 will be stopped because of the passive-interface
Serial0/0 configuration statement.
D. Both outgoing and incoming routing updates on R1 will be permitted because the distribute-list 20 out
Serial0/0 command cannot be used with association with the outgoing interface.
Answer: C
You can use the passive-interface command to control the advertisement of routing information. The
command enables the suppression of routing updates over some interfaces while it allows updates to be
exchanged normally over other interfaces. With most routing protocols, the passive-interface command
restricts outgoing advertisements only. However, when used with Enhanced Interior Gateway Routing
Protocol (EIGRP), the effect is slightly different. With EIGRP running on a network, the passive-
interface command stops both outgoing and incoming routing updates, since the effect of the command
causes the router to stop sending and receiving hello packets over an interface.
More on: Link1
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What does the default value of the EIGRP variance command of 1 mean?
A. Load balancing is disabled on this router.
B. The router performs equal-cost load balancing.
C. Only the path that is the feasible successor should be used.
D. The router only performs equal-cost load balancing on all paths that have a metric greater than 1.
Answer: B
The point of the question is about the load balancing configuration of EIGRP. If variance is 1, it means
that it support Equal cost path.
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Answer:
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Refer to the exhibit. EIGRP has been configured on all routers in the network. What additional
configuration statement should be included on router R4 to advertise a default route to its neighbors?
hostname R4 !
router eigrp 4
netowork 10.0.0.0 no auto-summary
A. R4(config)# ip route 0.0.0.0 0.0.0.0 10.1.1.1
B. R4(config)# ip default-network 10.0.0.0
C. R4(config-router)# default-information originate
D. R4(config)# ip route 10.0.0.0 255.0.0.0 10.1.1.1
Answer: B
Unlike the ip default-gateway command, you can use ip default-network when ip routing is enabled on
the Cisco router. When you configure ip default-network the router considers routes to that network for
installation as the gateway of last resort on the router.
For every network configured with ip default-network , if a router has a route to that network, that route
is flagged as a candidate default route. Gateways of last resort selected using the ip default-network
command are propagated differently depending on which routing protocol is propagating the default
route.
For IGRP and EIGRP to propagate the route, the network specified by the ip default-network command
must be known to IGRP or EIGRP. This means the network must be an IGRP- or EIGRP-derived network
in the routing table, or the static route used to generate the route to the network must be redistributed into
IGRP or EIGRP, or advertised into these protocols using the network command. In this case, the 10.0.0.0
network is indeed being advertised via EIGRP.
More on: Link1
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Which three networks is the router at 172.17.10.2 directly connected to? (Choose three)
Core#1show ip eigrp topology all-links IP EIGRP Topology table for AS(65001)/ID(172.17.10.1)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status
P 172.17.3.128/25, 2 succussors, FD is 30720, semo 9 via 172.17.10.2 (30720/28160), FastEthernet0/1
via 172.17.3.2 (30720/28160), FastEthernet0/3
P 10.140.0.0/21, 1 succussors, FD is 156160, semo 16 via 172.17.3.2 (156160/128256), FastEthernet0/3
via 172.17.10.2 (157720/155160), FastEthernet0/1
P 172.17.10.0/24, 1 succussors, FD is 28160, semo 1 via Connected, FastEthernet0/1
P 172.17.0.0/30, 1 succussors, FD is 20514560, semo 15
via 172.17.1.1 (20514560/205122000), FastEthernet0/2 via 172.17.10.2 (20516120/20513560), FastEthernet0/1
P 172.17.1.0/24, 1 succussors, FD is 28160, semo 2
via Connected, FastEthernet0/2 P 172.17.2.0/24, 1 succussors, FD is 30720, semo 8
via 172.17.10.2 (30720/28160), FastEthernet0/1
via 172.17.3.2 (33280/30720), FastEthernet0/3 P 172.17.3.0/25, 1 succussors, FD is 28160, semo 3
via Connected, FastEthernet0/3
A. 172.17.0.0/30
B. 172.17.1.0/24
C. 172.17.2.0/24
D. 172.17.3.0/25
E. 172.17.3.128/25
F. 172.17.10.0/24
Answer: C, E, F
On 172.17.10.2/24 interface we got router that in its routing table will have routes to the successor
networks for Core router (successor is next hop router for Core) and route connected directly to Core
network: 172.17.3.128/25; 172.17.2.0/24 and 172.17.10.0 (marked with red on the graphic).
Regarding information form topology table, we can draw following graphic:
CCNP Route 642-902 Questions/Answers - EIGRP
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CCNP Route 642-902 Questions/Answers - EIGRP
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show eigrp command and related information
Answer:
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Place in proper order following EIGRP terms.
Answer:
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Click and Drag the associated EIGRP functionality oh the left to the corresponding topology
charactersitics on the right.
Answer:
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Answer:
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Refer to the exihibit.What happens when the router stops receiving advertisements for the 10.1.2.0/24
network?
Router#show ip route
C 10.1.3.0/24 is directly connected, Serial2
D 10.1.2.0/24 [90/10597472] via 10.1.1.2, 00:23:24, Serial1
D 10.0.0.0/8 is a summary, 00:23:20, Null0 C 10.1.1.0/24 is directly connected, Serial1
S 192.168.20.0/24 is directly connected, Ethernet0
A. The summary route will be removed from the table.
B. The more specific routes will be advertised from the table.
C. The summary route will remain in the table.
D. 10.1.2.0/24 will still be advertised but packets destined for it will be dropped when they reach this
router.
Answer: C
When a router loses a route, it looks at the topology table for an FS. If one is available, the route does not
go into an active state. Instead, the best FS is promoted as the successor and is installed in the routing
table. The FS can be used immediately, without any recalculation. If there are no FSs, a route goes into
active state, and route computation occurs. Through this process, a new successor is determined (if there
is one). The amount of time it takes to recalculate the route affects the convergence time.
We have two networks that are directly connected to the router: 10.1.3.0/24 and 10.1.1.0/24. Because auto
summary is enabled by default in EIGRP routing domain, summary routes for this two networks will be
the same: 10.0.0.0/8, pointed to the Null0 interface.
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There was an exhibit,172.16.1.0/24 to 172.16.2.0/24 with the 4 paths with mentions of EIGRP metric and
asked if the varince is put to 2 in exhibit then what 2 paths are not used by EIGRP routing table? (Choose
two.)
R1#
router eigrp 110
variance 2
A. R1----R2----R6
B. R1----R3----R6
C. R1----R4----R6
D. R1----R5----R6
Answer: C, D
For easier computation it is better to put all information in the table. Next table contains all information
related to get the answer of the question.
Path Feasible Distance
(FD)
Advertised Distance
(AD)
Successor
Feasible Successor (FS)
AD(FS)<FD (S)
Unequal Load Balancing Path
(variance 2)
FD(Feasible)<2*FD (S)
R1-R2-R6 30 10 FS1: 10<20 Feasible:30<2*20
R1-R3-R6 20 10 S S
R1-R4-R6 45 25
R1-R5-R6 50 10 FS2: 10<20
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In routing table will be placed Successor route and Feasible route. Which of the following are true?
(Choose three)
A. For Frame Relay point-to-point interfaces, set the bandwidth to the CIR.
B. For Frame Relay point-to-point interfaces set the bandwidth to the sum of all CIRs.
C. For Frame Relay multipoint connections, set the bandwidth to the sum of all CIRs.
D. For generic serial interfaces such as PPP and HDLC, set the bandwidth to match the line speed.
E. For Frame Relay multipoint connections, set the bandwidth to the CIR.
Answer: A, C, D
By default, EIGRP uses up to 50 percent of the bandwidth declared on an interface or subinterface.
EIGRP uses the bandwidth of the link set by the bandwidth command, or the link’s default bandwidth if
none is configured, when calculating how much bandwidth to use. You can adjust this percentage on an
interface or subinterface with the ip bandwidth-percent eigrp as-number percent interface configuration
command. The as-number is the EIGRP autonomous system number. The percent parameter is the
percentage of the configured bandwidth that EIGRP can use. You can set the percentage to a value greater
than 100, which might be useful if the bandwidth is configured artificially low for routing policy reasons.
The Cisco IOS assumes that point-to-point Frame Relay subinterfaces are operating at the default speed
of the interface. In many implementations, however, only fractional speeds (such as a fractional T1) are
available. Therefore, when configuring these subinterfaces, set the bandwidth to match the contracted
CIR.
When configuring multipoint interfaces (especially for Frame Relay, but also for ATM and ISDN PRI),
remember that the bandwidth is shared equally by all neighbors. That is, EIGRP uses the bandwidth
command on the physical interface divided by the number of Frame Relay neighbors connected on that
physical interface to get the bandwidth attributed to each neighbor. EIGRP configuration should reflect
the correct percentage of the actual available bandwidth on the line.
Each installation has a unique topology, and with that comes unique configurations. Differing CIR values
often require a hybrid configuration that blends the characteristics of point-to-point circuits with
multipoint circuits. When configuring multipoint interfaces, configure the bandwidth to represent the
minimum CIR times the number of circuits. This approach might not fully use the higher-speed circuits,
but it ensures that the circuits with the lowest CIR will not be overdriven. If the topology has a small
number of very low-speed circuits, these interfaces are typically defined as point-to-point so that their
bandwidth can be set to match the provisioned CIR.
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R1 and R2 are connected and are running EIGRP on all their interfaces,
R1 has four interfaces,with IP address 172.16.1.1/24, 172.16.2.3/24, 172.16.5.1/24, and 10.1.1.1/24.
R2 has two interfaces, with IP address 172.16.1.2/24 and 192.168.1.1/24.
There are other routers in the network that are connected on each of the interfaces of these two routers
that are also running EIGRP. Which summary routes does R1 generate automatically (assuming auto-
summarization is enabled)? (Choose two.)
A. 192.168.1.0/24
B. 10.0.0.0/8
C. 172.16.1.0/22
D. 172.16.0.0/16
E. 10.1.1.0/24
Answer: B, D
When auto-summary is configured router makes summary routes pointed to Null0 interface.
R1 have interfaces with IP addresses: 172.16.1.1/24, 172.16.2.3/24, 172.16.5.1/24, and 10.1.1.1/24. When
EIGRP is used as routing protocol and auto-summarization is enabled, then networks: 172.16.1.0/24,
172.16.2.0/24 and 172.16.5.0/24 will be summarized with network 172.160.0/16. Network 10.1.1.1/24
will be summarized with 10.0.0.0/8 summary network.
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Which are the characteristics of the routing protocol EIGRP? (Choose two.)
A. Updates are sent as broadcast.
B. Updates are sent as multicast.
C. LSAs are sent to adjacent neighbors.
D. Metric values are represented in a 32-bit format for granularity.
Answer: B, D
EIGRP uses five packet types:
- Hello/Acks
- Updates
- Queries
- Replies
- Requests
As stated earlier, hellos are multicast for neighbor discovery/recovery. They do not require
acknowledgment. A hello with no data is also used as an acknowledgment (ack). Acks are always sent
using a unicast address and contain a non-zero acknowledgment number.
Updates are used to convey reachability of destinations. When a new neighbor is discovered, update
packets are sent so the neighbor can build up its topology table. In this case, update packets are unicast. In
other cases, such as a link cost change, updates are multicast. Updates are always transmitted reliably.
Queries and replies are sent when destinations go into Active state. Queries are always multicast unless
they are sent in response to a received query. In this case, it is unicast back to the successor that
originated the query. Replies are always sent in response to queries to indicate to the originator that it
does not need to go into Active state because it has feasible successors. Replies are unicast to the
originator of the query. Both queries and replies are transmitted reliably.
Request packets are used to get specific information from one or more neighbors. Request packets are
used in route server applications. They can be multicast or unicast. Requests are transmitted unreliably.
More on: Link1
CCNP Route 642-902 Questions/Answers - EIGRP
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Refer to the exhibit. BigBids Incorporated is a worldwide auction provider. The network uses EIGRP as
its routing protocol throughout the corporation. The network administrator does not understand the
convergence of EIGRP. Using the output of the show ip eigrp topology all-links command, answer the
administrator’s questions.
Core#show ip eigrp topology all-links
IP EIGRP Topology table for AS(65001)/ID(172.17.10.1)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 172.17.3.128/25, 2 seccussors, FD is 30720, semo 9
via 172.17.10.2 (30720/28160), FastEthernet0/1 via 172.17.3.2 (30720/28160), FastEthernet0/3
P 10.140.0.0/21, 1 seccussors, FD is 156160, semo 16
via 172.17.3.2 (156160/128256), FastEthernet0/3 via 172.17.10.2 (157720/155160), FastEthernet0/1
P 172.17.10.0/24, 1 seccussors, FD is 28160, semo 1
via Connected, FastEthernet0/1 P 172.17.0.0/30, 1 seccussors, FD is 20514560, semo 15
via 172.17.1.1 (20514560/20512200), FastEthernet0/2 via 172.17.10.2 (20516120/20513560), FastEthernet0/1
P 172.17.1.0/24, 1 seccussors, FD is 28160, semo 2
via Connected, FastEthernet0/2 P 172.17.2.0/24, 1 seccussors, FD is 30720, semo 8
via 172.17.10.2 (30720/28160), FastEthernet0/1
via 172.17.3.2 (33280/30720), FastEthernet0/3 P 172.17.3.0/25, 1 seccussors, FD is 28160, semo 3
via Connected, FastEthernet0/3
Which two networks does the Core device have feasible successors for? (Choose two)
A. 172.17.0.0/30
B. 172.17.1.0/24
C. 172.17.2.0/24
D. 172.17.3.0/25
E. 172.17.3.128/25
F. 10.140.0.0/24
Answer: A, F
For easier computation it is better to put all information in the table. Next table contains all information
related to get the answer of the question.
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Path
Through Core’s
(or via next hop IP
address)
Feasible
Distance
(FD)
Advertised
Distance
(AD)
Successor
Feasible Successor
(FS)
AD(FS)<FD (S)
to 172.17.3.128/25 fa0/1 (172.17.10.2/24) 30720 28160 S
fa0/3 (172.17.3.2/25) 30720 28160 S
to 10.140.0.0/21 fa0/1 (172.17.10.2/24) 156160 128256 FS: 128256<157720
fa0/3 (172.17.3.2/25) 157720 155160 S
to 172.17.0.0/30 fa0/1 (172.17.10.2/24) 20516120 20513560 FS: 20513560<20514560
fa0/2 (172.17.1.1/24) 20514560 20512200 S
to 172.17.2.0/24 fa0/1 (172.17.10.2/24) 30720 28160 S
fa0/3 (172.17.3.2/25) 33280 30720
Regarding information form topology table, we can draw following graphic:
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Refer to the exhibits. Router B should advertise the network connected to the E0/0/0 interface to router A
and block all other network advertisements. The IP routing table on router A indicates that it is not
receiving this prefix from router B. What is the probable cause of the problem?
RouterB#show ip eigrp neighbors
IP-EIUGRP neighbors for process 1
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num 0 10.255.1.1 Se0/0 138 00:15:26 26 582 0 3
RouterB#
RouterB#debug ip eigrp
IP-EIUGRP Route Events debugging is on 02:17:54: IP-EIUGRP: 192.168.3.16/28 - denied by distribute list
02:17:54: IP-EIUGRP: 192.168.3.32/28 - denied by distribute list
02:17:54: IP-EIUGRP: 10.255.1.0/30 - denied by distribute list
02:17:54: IP-EIUGRP: 192.168.3.0/24 - denied by distribute list
02:17:54: IP-EIUGRP: 10.0.0.0/8 - denied by distribute list
A. An access list on router B is causing the 192.168.3.16/28 network to be denied.
B. An access list on router B is causing the 192.168.3.32/28 network to be denied.
C. The distribute list on router B is referencing a numbered access list that does not exist on router B.
D. The distribute list on router B is referencing the wrong interface.
Answer: A
Network 192.168.3.21/28 has following usable IP addresses: 192.168.3.17 - 192.168.3.30. Subnet IP
address is: 192.168.3.16/28.
From: RouterB#debug ip eigrp command we can see that, this network is denied by distribute list
(marked with red):
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RouterB#debug ip eigrp
IP-EIUGRP Route Events debugging is on
02:17:54: IP-EIUGRP: 192.168.3.16/28 - denied by distribute list
02:17:54: IP-EIUGRP: 192.168.3.32/28 - denied by distribute list …
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When a primary route fails, what will be used? (EIGRP)
A. Administrative distance
B. Successor
C. Feasible
D. Feasible Successor
Answer: D
When a router loses a route, it looks at the topology table for an FS. If one is available, the route does not
go into an active state. Instead, the best FS is promoted as the successor and is installed in the routing
table. The FS can be used immediately, without any recalculation. If there are no FSs, a route goes into
active state, and route computation occurs. Through this process, a new successor is determined (if there
is one). The amount of time it takes to recalculate the route affects the convergence time.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 110
Under EIGRP, what is the use of the show ip protocol command?
A. to verify the IP connectivity to neighbor routers under EIGRP
B. able to see K values for EIGRP AS routing domain.
C. to see number of routing hops to the feasible successor
D. to calculate administrative distance of 90 for any route
Answer: B
Output of show ip protocol command is shown below:
Rack17SW1#sh ip proto
*** IP Routing is NSF aware ***
Routing Protocol is ―eigrp 10″
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
EIGRP maximum hopcount 100
EIGRP maximum metric variance 1
Redistributing: eigrp 10
EIGRP NSF-aware route hold timer is 240s
Automatic network summarization is not in effect
Maximum path: 4
Routing for Networks:
0.0.0.0
Routing Information Sources:
Gateway Distance Last Update
156.17.27.2 90 00:24:46
156.17.67.6 90 00:24:46
Distance: internal 90 external 170
CCNP Route 642-902 Questions/Answers - EIGRP
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What’s the AD of EIGRP summarized routes?
A. 90
B. 170
C. 110
D. default AD of summarized EIGRP routes is 5
Answer: D
More on: Link1
CCNP Route 642-902 Questions/Answers - EIGRP
2013 112
How will OSPF routes appear in the routing table after you redistribute them into EIGRP?
A. O IA
B. D EX
C. O
D. D EX*
Answer: B
Redistributed routes into EIGRP are denoted with D EX in the output statements in show ip route
command.
More on: Link1
CCNP Route 642-902 Questions/Answers - EIGRP
2013 113
Using the diagram below, in and EIGRP network, which paths will be choosen from router A to router H
with a varamce of 2?
A. A-D-E-H
B. A-B-C-H
C. A-B-E-H
D. A-F-E-H
E. A-F-G-H
Answer: A, D
For easier computation it is better to put all information in the table. Next table contains all information
related to get the answer of the question.
Path Feasible Distance
(FD)
Advertised Distance
(AD)
Successor
Feasible Successor
(FS) AD(FS)<FD (S)
Unequal Load Balancing Path (variance 2)
FD(Feasible)<2*FD (S)
A-D-E-H 30 20 S S
A-D-E-B-C-H 60 50
A-D-E-F-G-H 70 60
A-B-C-H 70 30
A-B-E-H 60 20 FS1: 20<30
A-B-E-F-G-H 100 60
A-F-G-H 60 40
A-F-E-H 40 20 FS2: 20<30 Feasible: 40<2*30
A-F-E-B-C-H 70 50
We have one successor route that will be in the routing table. After configuring router A with variance 2
in routing table we will got another route called feasible (A-F-E-H). That means that we will get non-
equal cost path load balancing through two paths.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 114
When configuring EIGRP to run across a 56Kbps serial PPP link, what command do you need to put
under the serial interface to ensure proper convergence of EIGRP routes? (Choose one)
A. bandwidth 56
B. bandwidth 56000
C. ip bandwidth-percent eigrp 1 56
D. ip bandwidth-percent eigrp 1 56000
Answer: A
When configuring serial links using EIGRP it is important to configure the bandwidth setting onthe
interface. If the bandwidth setting is not changed for these interfaces EIGRP assumes the default
bandwidth on the link instead of the true bandwidth. If the link is slower, the router may not be able to
converge, routing updates might become lost, or suboptimal path selection may result.
Example:
Router(config-if)#bandwidth kilobits
The value, kilobits, indicates the intended bandwidth in kilobits per second. For generic serial interfaces,
such as PPP or HDLC, set the bandwidth to the line speed.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 115
Routers in the diagram are configured with EIGRP. If routers RTB and RTC fail, which action will RTA
take with respect to the HQ network?
A. RTA will automatically route packets via RTD to the HQ network.
B. RTA will place the route via RTD into the hold down state.
C. RTA will go into the active state for all routers.
D. RTA will go into the active state for the route to the HQ network.
Answer: D
For easier computation it is better to put all information in the table. Next table contains all information
related to get the answer of the question.
Path Feasible Distance
(FD)
Advertised Distance
(AD)
Successor
Feasible Successor (FS)
AD(FS)<FD (S)
RTA-RTB-HQ
Network 40 30 FS: 30<31
RTA-RTC-HQ
Network 31 21 S
RTA-RTD-HQ Network
230 220
We have one successor route that will be in the routing table and one feasible successor.
Successor is RTC, and feasible successor RTB. When routers RTB and RTC fail one remaining route to
the HQ network is through router RTD. We can see that route through RTD is not satisfying criteria for
FS. That means that this route can’t be placed in the routing table as successor (if FS fails). Because RTA
can’t find FS, it starts active state for the route to HQ network.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 116
Which of the following are methods EIGRP uses to initially populate (seed) its EIGRP topology table,
before learning topology data from neighbors? (Choose two.)
A. By adding all subnets listed by the show ip route connected command
B. By adding the subnets of working interfaces over which static neighbors have been defined
C. By adding subnets redistributed on the local router from another routing source
D. By adding all subnets listed by the show ip route static command
Answer: B, C
Other than the two listed correct answers, the local router also adds connected routes for which the
network command matches the corresponding interfaces, so it may not add all connected routes. Also,
EIGRP does not add static routes to the EIGRP topology table, unless those routes are redistributed.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 117
An engineer has added the following configuration snippet to an implementation planning document. The
configuration will be added to Router R1, whose Fa0/0 interface connects to a LAN to which Routers R2
and R3 also connect. R2 and R3 are already EIGRP neighbors with each other. Assuming the snippet
shows all commands on R1 related to EIGRP authentication, which answer lists an appropriate comment
to be made during the implementation plan peer review?
key chain fred
key 3
key-string whehew interface fa0/0
ip authentication key-chain eigrp 9 fred
A. The configuration is missing one authentication-related configuration command.
B. The configuration is missing two authentication-related configuration commands.
C. Authentication type 9 is not supported; type 5 should be used instead
D. The key numbers must begin with key 1, so change the key 3 command to key 1.
Answer: A
The configuration requires the ip authentication mode eigrp asn md5 command, which is currently
missing. This command enables MD5-style authentication, rather than the default of no authentication.
Adding this one command completes the configuration. Any valid key numbers can be used. Also, the 9
in the ip authentication key-chain eigrp 9 fred command refers to the EIGRP ASN, not an authentication
type.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 118
Which of the following settings could prevent two potential EIGRP neighbors from becoming neighbors?
(Choose two answers.)
A. The interface used by one router to connect to the other router is passive in the EIGRP process.
B. Duplicate EIGRP router IDs
C. Mismatched Hold Timers.
D. IP addresses of 10.1.1.1/24 and 10.2.2.2/24, respectively.
Answer: A, D
- Duplicate Enhanced Interior Gateway Routing Protocol (EIGRP) router IDs can cause problems with the
redistribution of EIGRP external routes. The EIGRP router ID is normally selected in the same manner as
Open Shortest Path First (OSPF). The highest IP address assigned to a loopback interface is selected as
the router ID. If there are not any loopback addresses configured, the highest IP address assigned to any
other interface is chosen as the router ID.
- The passive-interface {type number} | default router configuration command prevents a routing
protocol’s routing updates from being sent through the specified router interface. This command is used
to set either a particular interface or all router interfaces to passive; use the default option to set all router
interfaces to passive. For EIGRP, the passive-interface command does the following:
• It prevents a neighbor relationship from being established over a passive interface.
• It stops routing updates from being processed or sent over passive interface.
• It allows a subnet on a passive interface to be announced in an EIGRP process.
- Two routers can become EIGRP neighbors even though the hello and hold time values do not match.
This means that the hello interval and hold-time values can be set independently on different routers.
Secondary addresses can be applied to interfaces to solve particular addressing issues, although all routing
overhead traffic is generated through the primary interface address. EIGRP will not build peer
relationships over secondary addresses because all EIGRP traffic uses the interface’s primary address. To
form an EIGRP adjacency, all neighbors use their primary address as the source IP address of their
EIGRP packets. Adjacency between EIGRP routers takes place if the primary address of each neighbor is
part of the same IP subnet. In addition, peer relationships are not formed if the neighbor resides in a
different EIGRP autonomous system or if the metric-calculation mechanism constants (the K values) are
misaligned on that link.
- Two routers to form adjacency must configure their interface, used for forming link between them, with
valid IP address from the same subnet.
More on: Link1
CCNP Route 642-902 Questions/Answers - EIGRP
2013 119
A network administrator is managing a hub-and-spoke network with EIGRP routing that has been
enabled. The hub router is trying to query a remote router. However, delays are occurring that are caused
by certain paths being stuck in active (SIA). How should the administrator configure EIGRP in order to
limit the scope of the query range and prevent SIA from occurring?
A. Configure the hub router with a scope limit of 1.
B. Configure the remote router with a scope limit of 1.
C. Configure the hub to indicate that the remote router is a stub router.
D. Configure the hub and remote router as stub routers.
E. Configure the remote router as a stub router.
F. Disable the SIA feature of EIGRP on the remote router.
Answer: E
Limiting the scope of query propagation through the network (the query range), also known as query
scoping, helps reduce incidences of SIA. Keeping the query packets close to the source reduces the
chance that an isolated failure in another part of the network will restrict the convergence (query/reply)
process. This section introduces an example that examines how to manage the query range.
Hub-and-spoke network topologies commonly use stub routing. In this topology, the remote router
forwards all traffic that is not local to a hub router, so the remote router does not need to retain a complete
routing table. Generally, the hub router needs to send only a default route to the remote routers. EIGRP
stub routing should be used on stub routers only. A stub router is defined as a router connected to the
network core or hub layer, and through which core transit traffic should not flow. A stub router should
have only hub routers for EIGRP neighbors. Ignoring this restriction causes undesirable behavior.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 120
What are two possible causes for EIGRP Stuck-In-Active routers? (Choose Two)
A. Some query or reply packets are lost between the routers.
B. The neighboring router starts receiving route updates from this router.
C. A failure causes traffic on a link between two neighboring routers to flow in only one direction
(unidirectional link).
D. The neighboring router stops receiving ACK packets from this router.
Answer; A, C
As an advanced distance vector routing protocol, EIGRP relies on its neighbors to provide routing
information. Recall that when a router loses a route and does not have an FS in its topology table, it looks
for an alternative path to the destination. This is known as going active on a route. (Recall that a route is
considered passive when a router is not recomputing that route.) Recomputing a route involves sending
query packets to all neighbors on interfaces other than the one used to reach the previous successor
because of split horizon), inquiring whether they have a route to the given destination. If a router has an
alternative route, it answers the query with a reply packet and does not propagate the query further. The
reply includes the alternate route. If a neighbor does not have an alternative route, it queries each of its
own neighbors for an alternative path. The queries then propagate through the network, thus creating an
expanding tree of queries. When a router answers a query, it stops the spread of the query through that
branch of the network. However, the query can still spread through other portions of the network as other
routers attempt to find alternative paths, which might not exist.
Troubleshooting SIA routes is more of an art form than a science, but there are four main reasons a route
becomes SIA:
- The link is unidirectional, so the query can´t possibly be answered.
- The queried router´s resources are unavailable, generally due to high CPU utilization.
- The queried router´s memory is corrupt or otherwise unable to allow the router to answer the query.
- The link between the two routers is of low quality, allowing just enough packets through to keep the
neighbor relationship intact, but not good enough to allow the replies through.
- To sum it up, routes generally become SIA when a neighbor either doesn´t answer a query, or either the
query or reply took a wrong turn somewhere. It wasn´t the easiest thing to troubleshoot!
CCNP Route 642-902 Questions/Answers - EIGRP
2013 121
In EIGRP, when the ip default-network command is configured on a router, what is generated in the
router's configuration?
A. A static route
B. A directly connected route
C. An EIGRP route
D. A default route
Answer: D
Alternatively, any major network residing in the local routing table can become an EIGRP default route
when used in the ip default-network network-number global configuration command. A router configured
with this command considers the network-number the last-resort gateway that it will announce to other
routers with the exterior flag set. The network must be reachable by the router that uses this command
before it announces it as a candidate default route to other EIGRP routers. The network number in this
command must also be passed to other EIGRP routers so that those routers can use this network as their
default network and set their gateway of last resort to this default network. This means that the network
must either be an EIGRP-derived network in the routing table, or be generated with a static route and
redistributed into EIGRP.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 122
Which router configuration command can be given that will restrict router RTB from sharing its routing
information with router RTA?
RTB
ip route 10.1.4.0 255.255.255.0 10.1.3.10
interface serial 0/0
ip summary-address eigrp 100 10.1.2.0 255.255.254.0
router eigrp 100
no auto-summary
redistribute static metric 10000 1 255 1 1500 network 10.1.1.0 0.0.0.3
network 10.1.2.0 0.0.0.255
A. the eigrp stub command on router RTA
B. the eigrp stub command on router RTB
C. the eigrp stub connected command on router RTA
D. the eigrp stub connected command on router RTB
E. the eigrp stub receive-only command on router RTA
F. the eigrp stub receive-only command on router RTB
Answer: F
To configure a router as an EIGRP stub, use the eigrp stub [receive-only | connected | static | summary
|redistributed] router configuration command. A router configured as a stub with the eigrp stub command
shares information about connected and summary routes with all neighbor routers by default.
In our case it is needed receive-only parameter to restrict router RTB from sharing its routing information
with router RTA.
CCNP Route 642-902 Questions/Answers - EIGRP
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receive-only - The receive-only keyword restricts the router from sharing any of its routes with any other
router within an EIGRP autonomous system. This keyword does not permit any other keyword to be
specified, because it prevents any type of route from being sent. Use this option if there is a single
interface on the router.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 124
Which two types of routes will be advertised with the EIGRP configuration as shown? (Choose two.)
router eigrp 100 network 10.0.0.0
eigrp stub
A. static
B. receive-only
C. summary
D. stub
E. connected
F. dynamic
Answer: C, E
A router configured as a stub with the eigrp stub command shares information about connected and
summary routes with all neighbor routers by default.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 125
On all routers in the network, EIGRP has been configured for load balancing across the three links.
However, traffic destined for Network B from R1 is only load balanced over paths R1-R2-R5 and R1-R3-
R5. What is the cause of the problem?
hostname R1
!
router eigrp 4 network 10.0.0.0
variance 3
A. EIGRP will not select more than two links for unequal cost path load balancing.
B. Because the path has a different link type, EIGRP will not select path R1-R4-R5 for load balancing.
C. Because Router R4 is not a feasible successor, EIGRP will not select path R1-R4-R5 for load
balancing.
D. EIGRP will not select path R1-R4-R5 for load balancing unless the value of the variance parameter is
increased.
Answer: C
For easier computation it is better to put all information in the table. Next table contains all information
related to get the answer of the question.
Path
Feasible
Distance
(FD)
Advertised
Distance
(AD)
Successor
Feasible
Successor (FS)
AD(FS)<FD (S)
Unequal Load Balancing Path
(variance 3)
FD(Feasible)<3*FD (S)
R1-R4-R5 45 25
R1-R3-R5 30 10 FS: 10<20 FS
R1-R2-R5 20 10 S S
CCNP Route 642-902 Questions/Answers - EIGRP
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As we can see from the table, we have on successor and one feasible successor. We don’t have feasible
route.
To have unequal cost load balancing feasible route two feasibility condition must be satisfied:
1) The route must be loop free. As noted earlier, this means that the best metric (the AD) learned
from the next router must be less than the local best metric (the current FD). In other words, the
next router in the path must be closer to the destination than the current router.
2) The metric of the entire path (the FD of the alternative route) must be lower than the variance
multiplied by the local best metric (the current FD). In other words, the metric for the entire
alternate path must be within the variance.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 127
Identify three characteristics of EIGRP feasible successors? (Choose three.)
A. A feasible successor is selected by comparing the advertised distance of a non-successor route to the
feasible distance of the best route.
B. If the advertised distance of the non-successor route is less than the feasible distance of best route, then
that route is identified as a feasible successor.
C. The feasible successor can be found in the routing table.
D. If the successor becomes unavailable, then the feasible successor can be used immediately without
recalculating for a lost route.
E. Traffic will be load balanced between feasible successors with the same advertised distance.
Answer: A, B, D
To qualify as an FS, a next-hop router must have an AD less than the FD of the current successor route
for the particular network. This is known as the feasibility condition. This requirement ensures that the FS
cannot use a route through the local router (which would be a routing loop), because the AD through the
FS is less than the best route through the local router.
When a router loses a route, it looks at the topology table for an FS. If one is available, the route does not
go into an active state. Instead, the best FS is promoted as the successor and is installed in the routing
table. The FS can be used immediately, without any recalculation. If there are no FSs, a route goes into
active state, and route computation occurs. Through this process, a new successor is determined (if there
is one). The amount of time it takes to recalculate the route affects the convergence time.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 128
Which three features are related to EIGRP? (Choose three)
A. Fast Convergence
B. External Administrative distance is 100
C. Partial routing updates.
D. Used by other vendors than Cisco.
E. Link-state protocol.
F. Support VLSM and discontiguous subnets
Answer: A, C, F
Features of EIGRP protocol include the following:
- Fast convergence - EIGRP uses DUAL to achieve rapid convergence. A router running EIGRP stores
its neighbors’ routing tables so that it can quickly adapt to changes in the network. If no appropriate route
exists in the local routing table and no appropriate backup route exists in the topology table, EIGRP
queries its neighbors to discover an alternative route. These queries are propagated until an alternative
route is found or until it is determined that no alternative route exists.
- Partial updates - EIGRP sends partial triggered updates rather than periodic updates. These updates are
sent only when the path or the metric for a route changes. They contain information about only that
changed link rather than the entire routing table. Propagation of these partial updates is automatically
bounded so that only those routers that require the information are updated. As a result, EIGRP consumes
significantly less bandwidth than IGRP. This behavior is also different from link-state protocol operation,
which sends a change update to all routers within an area.
- Multiple network layer support - EIGRP supports IP Version 4 (IPv4), IP Version 6 (IPv6), AppleTalk,
and Novell NetWare Internetwork Packet Exchange (IPX) using protocol-dependent modules that are
responsible for protocol requirements specific to the network layer. EIGRP’s rapid convergence and
sophisticated metric offer superior performance and stability when implemented in IP, IPv6, IPX, and
AppleTalk networks.
Other EIGRP features include the following:
- Variable-length subnet masking (VLSM) support - EIGRP is a classless routing protocol, which means
that it advertises a subnet mask for each destination network. This enables EIGRP to support
discontinuous subnetworks and VLSM.
- Seamless connectivity across all data link layer protocols and topologies - EIGRP does not require
special configuration to work across any Layer 2 protocols. Other routing protocols, such as Open
Shortest Path First (OSPF), require different configurations for different Layer 2 protocols, such as
Ethernet and Frame Relay (as you will see in Chapter 3, ―Configuring the Open Shortest Path First
CCNP Route 642-902 Questions/Answers - EIGRP
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Protocol‖). EIGRP was designed to operate effectively in both LAN and WAN environments. In
multiaccess topologies, such as Ethernet, neighbor relationships (also known as neighborships) are
formed and maintained using reliable multicasting. EIGRP supports all WAN topologies: dedicated links,
point-to-point links, and nonbroadcast multiaccess (NBMA) topologies. EIGRP accommodates
differences in media types and speeds when neighbor adjacencies form across WAN links. The amount of
bandwidth that EIGRP uses on WAN links can be limited.
- Sophisticated metric - EIGRP uses the same algorithm for metric calculation as IGRP, but represents
values in a 32-bit format, rather than IGRP’s 24-bit format, to give additional granularity (thus, the
EIGRP metric is the IGRP metric multiplied by 256). A significant advantage of EIGRP (and IGRP) over
other protocols is its support for unequal metric load balancing that allows administrators to better
distribute traffic flow in their networks.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 130
Which of the below mentioned conditions form a neighbor relation in EIGRP? (Choose three)
A. Hello or ACK received
B. AS number match
C. Hello timer match
D. Identical metric (k values)
E. Dead Timer Match
F. Network Time Match
Answer: A, B, D
Two routers can become EIGRP neighbors even though the hello and hold time values do not match. This
means that the hello interval and hold-time values can be set independently on different routers.
EIGRP will not build peer relationships over secondary addresses because all EIGRP traffic uses the
interface’s primary address. To form an EIGRP adjacency, all neighbors use their primary address as the
source IP address of their EIGRP packets.
Adjacency between EIGRP routers takes place if the primary address of each neighbor is part of the same
IP subnet. In addition, peer relationships are not formed if the neighbor resides in a different EIGRP
autonomous system or if the metric-calculation mechanism constants (the K values) are misaligned on
that link.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 131
A stub area is typically created using what kind of topology?
A. Broadcast
B. Point-to-point
C. Hub and spoke
D. Full Mesh
Answer: C
A stub area is typically created using a hub-and-spoke topology, with a spoke being a stub area, such as a
branch office. In this case, the branch office does not need to know about every network at the
headquarters site, because it can use a default route to reach the networks.
CCNP Route 642-902 Questions/Answers - EIGRP
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Refer to the exhibit. Following table of RA contains FD and AD values for routes to the network B
(10.1.2.0/24). Variance is set to default for router RA.
Route FD AD
through RB 6674001 5470303
through RC 5362821 4195522
through RD 6801701 3907449
What will happen if successor becomes unavailable?
A. Router will load balance between feasible successors.
B. Route in RA will go into active state and send multicast queries to its neighbors.
C. Router RA will immediately send traffic to router RB, destined for network B.
D. Router RA will immediately send traffic to router RD, destined for network B.
Answer: D
For easier computation it is better to put all information in the table. Next table contains all information
related to get the answer of the question.
Path
Feasible
Distance (FD)
Advertised
Distance (AD)
Successor
Feasible Successor
(FS) AD(FS)<FD (S)
through RB 6674001 5470303
through RC 5362821 4195522 S
through RD 6801701 3907449 FS: 3907449<5362821
CCNP Route 642-902 Questions/Answers - EIGRP
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We have one successor route that will be in the routing table and one feasible successor route. If
successor router fails RA will use feasible successor (router RD) and will route immediately to the
destination network B, without route recomputation.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 134
Refer to the exhibit. Following table of RA contains FD and AD values for routes to the network B
(10.1.2.0/24). Variance is set to default for router RA.
Route FD AD
through RB 6674001 5470303
through RC 5362821 4195522
through RD 6801701 3907449
Which of the following statements are correct?
A. Router RD is the only feasible successor.
B. Router RB is the only feasible successor.
C. Routers RB and RC are feasible successors.
D. None of the routers is feasible successor.
Answer: A
For easier computation it is better to put all information in the table. Next table contains all information
related to get the answer of the question.
Path
Feasible
Distance
(FD)
Advertised
Distance
(AD)
Successor
Feasible Successor
(FS)
AD(FS)<FD (S)
through RB 6674001 5470303
through RC 5362821 4195522 S
through RD 6801701 3907449 FS: 3907449<5362821
CCNP Route 642-902 Questions/Answers - EIGRP
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We have one successor route that will be in the routing table and one feasible successor route. If
successor router fails RA will use feasible successor (router RD) and will route immediately to the
destination network B, without route recomputation.
CCNP Route 642-902 Questions/Answers - EIGRP
2013 136
Refer to the exhibit. Following table of RA contains FD and AD values for routes to the network B
(10.1.2.0/24). Variance is set to default for router RA.
Route FD AD
through RB 6674001 5470303
through RC 5362821 4195522
through RD 6801701 3907449
Which of the following routes to network B will be displayed when you issue show ip eigrp topology
command?
A. route through router RD
B. route through router RB
C. routes through router RB and RD
D. routes through router RC and RD
Answer: D
For easier computation it is better to put all information in the table. Next table contains all information
related to get the answer of the question.
Path Feasible Distance
(FD)
Advertised Distance
(AD)
Successor
Feasible Successor (FS)
AD(FS)<FD (S)
through RB 6674001 5470303
through RC 5362821 4195522 S
through RD 6801701 3907449 FS: 3907449<5362821
CCNP Route 642-902 Questions/Answers - EIGRP
2013 137
We have one successor route that will be in the routing table and one feasible successor route. In topology
table are placed successor and feasible successor routes.
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Refer to the exhibit. Following table of RA contains FD and AD values for routes to the network B
(10.1.2.0/24). Variance is set to default for router RA.
Route FD AD
through RB 6674001 5470303
through RC 5362821 4195522
through RD 6801701 3907449
What would happen if you issue variance 3 command on router RA?
A. Router RA will load balance through RB and RC paths.
B. Router RA will load balance through RB and RD paths.
C. Router RA will load balance through RC and RD paths.
D. Router RA will load balance through three equal cost paths.
Answer: C
For easier computation it is better to put all information in the table. Next table contains all information
related to get the answer of the question.
Path
Feasible
Distance (FD)
Advertised
Distance (AD)
Successor
Feasible Successor
(FS) AD(FS)<FD (S)
Unequal Load Balancing
Path
(variance 3)
FD(Feasible)<3*FD (S)
through RB 6674001 5470303
through RC 5362821 4195522 S S
through RD 6801701 3907449 FS: 3907449<5362821
Feasible:
6801701<3*5362821
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We have one successor route that will be in the routing table and one feasible successor route. When
using variance there is need to be satisfied two statements:
1) AD(FS)<FD (S)
2) FD(Feasible)<variance_value*FD (S)
These statements are satisfied by FS route through router RD. That means that RouterA will use unequal-
cost load balancing through two paths: through RC and through RD.
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Select each packet type from the column on the left that might be displayed when you issue the debug
eigrp packet command and drag it to the column on the right.
Answer:
More on: Link1
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Refer to the exhibit and the presented show commands outputs. You want to ensure that routing protocol
converges quickly as possible and to eliminate unnecessary consumption of network bandwidth. Which
statement is true?
R1#show ip interfaces brief
Interface IP-Address OK? Method Status Protocol
Ethernet0/0 unassigned YES manual up up Ethernet0/0.1 172.16.10.1 YES manual up up
Ethernet0/0.2 172.16.20.1 YES manual up up Ethernet0/0.3 172.16.30.1 YES manual up up
Ethernet0/0.4 172.16.40.1 YES manual up up
Ethernet0/0.5 172.16.50.1 YES manual up up Ethernet0/0.6 172.16.60.1 YES manual up up
Ethernet0/0.7 172.16.70.1 YES manual up up
Ethernet0/0.8 172.16.80.1 YES manual up up
Serial0 10.16.10.1 YES manual up up
Serial1 unassigned YES unset administratively down down
R3#sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route
Gateway of last resort is not set
172.16.0.0/24 is subnetted, 8 subnets
D 172.16.60.0 [90/2617271] via 10.1.1.1, 00:00:15, FastEthernet0/0 D 172.16.50.0 [90/2617271] via 10.1.1.1, 00:00:15, FastEthernet0/0
D 172.16.40.0 [90/2617271] via 10.1.1.1, 00:00:15, FastEthernet0/0
D 172.16.30.0 [90/2617271] via 10.1.1.1, 00:00:15, FastEthernet0/0 D 172.16.20.0 [90/2617271] via 10.1.1.1, 00:00:15, FastEthernet0/0
D 172.16.10.0 [90/2617271] via 10.1.1.1, 00:00:15, FastEthernet0/0
D 172.16.80.0 [90/2617271] via 10.1.1.1, 00:00:15, FastEthernet0/0 D 172.16.70.0 [90/2617271] via 10.1.1.1, 00:00:15, FastEthernet0/0
10.0.0.0/24 is subnetted, 8 subnets
D 10.16.10.0 [90/2328191] via 10.1.1.1, 00:00:15, FastEthernet0/0 D 10.16.10.16 is directly connected, FastEthernet0/0
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A. Change RIP with EIGRP on R3.
B. Issue EIGRP auto-summary command on router R1.
C. Issue EIGRP auto-summary command on router R3.
D. Change RIP with EIGRP on R1.
Answer: B
We can see that router R3 has learned 172.16.0.0/24 network routes from its interface FastEthernet0/0.
That means that these routes came from R1, because on R1 are configured interfaces with IP addresses
that belongs to these subnets, as we can see from R1#show ip interfaces brief command.
Because of that we have to issue EIGRP auto-summary command on router R1.
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Which of the following routing protocols support unequal-cost load balancing? (Choose two)
A. RIPv1
B. RIPv2
C. IGRP
D. EIGRP
E. OSPF
Answer: C, D
Equal cost load balancing is supported by: RIPv1, RIPv2, IGRP, EIGRP and OSPF.
Unequal cost load balancing is supported by: IGRP and EIGRP.
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In regard of the line statement from show ip route command, how route 100.1.1.0/24 was learned?
D EX 100.1.1.0/24 [170/22732821] via 10.1.1.1, 00:01:17, FastEthernet0/0
A. Route is redistributed into OSPF.
B. Route is redistributed into EIGRP.
C. Route is originated from EIGRP.
D. This route is static route.
E. Route is redistributed into RIP.
Answer: B
EIGRP routes are designated with D in the routing table. Routes that come from external AS (Autonomos
System) are designated with EX.
D EX 100.1.1.0/24 [170/22732821] via 10.1.1.1, 00:01:17, FastEthernet0/0
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Which of the following entries from show ip route command output indicates that default route is
redistributed into EIGRP?
A.
B.
C.
D.
Answer: D
D indicates that this is an EIGRP route. * indicates that this route is default route. EX indicates that the
route is external route (which is route redistributed into EIGRP). Address 0.0.0.0/0 specifies that any
packet that does not have a specific route in the routing table should be sent over this default route. The
first number in the square brackets 170 is administrative distance, which is used to determine the routing
protocol that should be preferred when multiple routes to a destination network exist. External EIGRP
routes have administrative distance of 170 by default.
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You issue the following block of commands on RouterA:
RouterA(config)#router eigrp 100
RouterA(config-router)#network 10.0.1.0 0.0.0.255
RouterA(config-router)#network 10.0.2.0 0.0.0.255
RouterA(config-router)#redistribute connected
RouterA(config-router)#no auto-summary
RouterA(config-router)#eigrp stub
From the column on the left, select the route types that RouterA will advertise to its peers and drag those
route types to the column on the right.
Answer:
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EIGRP stub router (configured with eigrp stub command) advertises summary and directly connected
routes. But, because no auto-summary command is issued on the router, summary routes aren’t going to
be advertised.
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2013 148
Which show command displays EIGRP hello, update, query, reply and acknowledgement packets as they
are sent and received?
A. show ip eigrp topology
B. show ip eigrp neighbors
C. debug eigrp packets
D. show ip eigrp traffic
Answer: C
Output of show ip eigrp topology is given below:
R1# show ip eigrp topology
IP-EIGRP Topology Table for AS(1)/ID(172.31.16.1)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status
P 172.31.151.0/24, 1 successors, FD is 768
via Connected, Loopback1 P 172.31.211.0/24, 1 successors, FD is 1024
via 172.31.11.201 (1024/768, FastEthernet0/0
P 172.31.24.0/30, 1 successors, FD is 768 via 172.31.11.2 (768/512), FastEthernet0/0
via 172.31.14.2 (1024/512), Serial0/0.4
! Lines omitted for brevity ! Below, the metric in the IP routing table entries match the first number in
! the parentheses, as well as the number listed as "FD is..." in the output above.
Output of show ip eigrp neighbors is given below:
RouterX# show ip eigrp neighbors
IP-EIGRP neighbors for process 100
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
1 10.23.23.2 Se0/0/1 13 00:02:26 29 2280 0 15
0 10.140.1.1 Se0/0/0 10 00:28:26 24 2280 0 25
Output of debug eigrp packets is given below:
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R2#debug eigrp packets
*May 11 04:20:43.361: EIGRP: Received QUERY on Serial0/0/1 nbr
192.168.1.101
*May 11 04:20:43.361: AS 100, Flags 0x0, Seq 6/5 idbQ 0/0 iidbQ un/rely
0/0 peerQ un/
rely 0/0
*May 11 04:20:43.361: EIGRP: Enqueueing ACK on Serial0/0/1 nbr
192.168.1.101
*May 11 04:20:43.361: Ack seq 6 iidbQ un/rely 0/0 peerQ un/rely 1/0
*May 11 04:20:43.365: EIGRP: Sending ACK on Serial0/0/1 nbr
192.168.1.101
*May 11 04:20:43.365: AS 100, Flags 0x0, Seq 0/6 idbQ 0/0 iidbQ un/rely
0/0 peerQ un/
rely 1/0
*May 11 04:20:43.373: EIGRP: Enqueueing REPLY on Serial0/0/1 nbr
192.168.1.101 iidbQ un/
rely 0/1 peerQ un/rely 0/0 serno 10-12
*May 11 04:20:43.377: EIGRP: Requeued unicast on Serial0/0/1
Output of show ip eigrp traffic is given below:
Router# show ip eigrp traffic
IP-EIGRP Traffic Statistics for process 77 Hellos sent/received: 218/205
Updates sent/received: 7/23
Queries sent/received: 2/0
Replies sent/received: 0/2
Acks sent/received: 21/14
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Which of the following parameters is used to calculate EIGRP metric? (Choose two)
A. total bandwidth
B. Average delay
C. Total delay
D. Minimum bandwidth
Answer: C, D
EIGRP uses minimum bandwidth and total delay in the calculation of metric weights or K values, by
default. Other K values are set to 0.
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Which routes are displayed in the EIGRP topology table as sourced from Null0 interface?
A. active routes
B. passive routes
C. summarized routes
D. directly connected routes
Answer: C
Output of the show ip eigrp topology command is given below:
Router# show ip eigrp topology
EIGRP-IPv4 Topology Table for AS(1)/ID(10.0.0.1)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - Reply status, s - sia status P 10.0.0.0/8, 1 successors, FD is 409600
via 1.1.1.2 (409600/128256), Ethernet0/0
P 172.16.1.0/24, 1 successors, FD is 409600 via 1.1.1.2 (409600/128256), Ethernet0/0
P 10.0.0.0/8, 1 successors, FD is 281600
via Summary (281600/0), Null0 P 10.0.1.0/24, 1 successors, FD is 281600
via Connected, Ethernet0/0
Summarized routes in topology table are displayed as sourced from Null0 interface, no matter if they are
automatically or manually summarized.
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Select the characteristics that apply to EIGRP from the left and drag them to the right.
Answer:
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Refer to the exhibit. EIGRP is configured on all routers. Commands that you have entered on routers RA,
RB and RC are:
RA(config)#interface fa0/0
RA(config-if)#ip authentication mode eigrp 19 md5
RA(config-if)#ip authentication key-chain eigrp 19 Pass_RA RA(config-if)#exit
RA(config-if)#key chain Pass_RA
RA(config-keychain)#key 1 RA(config-keychain-key)#key-string Pass_pass
RB(config)#interface fa0/0
RB(config-if)#ip authentication mode eigrp 19 md5
RB(config-if)#ip authentication key-chain eigrp 19 Pass_RB RB(config-if)#exit
RB(config)#interface fa0/1
RB(config-if)#ip authentication mode eigrp 19 md5 RB(config-if)#ip authentication key-chain eigrp 19 Pass_RB
RB(config-if)#exit
RB(config-if)#key chain Pass_RB RB(config-keychain)#key 2
RB(config-keychain-key)#key-string Pass_pass
RC(config)#interface fa0/1
RC(config-if)#ip authentication mode eigrp 19 md5 RC(config-if)#ip authentication key-chain eigrp 19 Pass_RC
RC(config-if)#exit
RC(config-if)#key chain Pass_RC RC(config-keychain)#key 2
RC(config-keychain-key)#key-string Pass_pass
What is the reason of lost connectivity?
A. Routers are configured into different EIGRP Ass.
B. Router RD is not configured with authentication
C. Key IDs do not match on RA and RB
D. Key chain names do not match on RA and RB
Answer: C
Key IDs do not match on router RA (key ID is 1) and RB (key ID is 2).
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Chain name is locally significant, so key chain names do not have to match between the neighboring
routers. In our case RA have key chain name Pass_RA and RB have key chain name Pass_RB.
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When you issue command eigrp stub, which routes are advertised by default?
A. summary routes
B. static routes
C. directly connected routes
D. directly connected routes and external routes
E. summary routes and directly connected routes
Answer: E
A router configured as a stub with the eigrp stub command shares information about connected and
summary routes with all neighbor routers by default.
Table 1describes the four optional keywords that can be used with the eigrp stub command to modify this
behavior.
Table 1. eigrp stub Command Parameters
receive-only - The receive-only keyword restricts the router from sharing any of its routes with any other
router within an EIGRP autonomous system. This keyword does not permit any other keyword to be
specified, because it prevents any type of route from being sent. Use this option if there is a single
interface on the router.
connected - The connected keyword permits the EIGRP stub routing feature to send connected routes. If
a network command does not include the connected routes, it might be necessary to redistribute
connected routes with the redistribute connected command under the EIGRP process. This option is
enabled by default and is the most widely practical stub option.
static - The static keyword permits the EIGRP stub routing feature to send static routes. Redistributing
static routes with the redistribute static command is still necessary.
summary - The summary keyword permits the EIGRP stub routing feature to send summary routes. You
can create summary routes manually with the ip summary-address eigrp command or automatically at a
major network border router with the auto-summary command enabled. This option is enabled by default.
redistributed - The redistribute option permits the EIGRP stub routing feature to send redistributed
routes. Redistributing routes with the redistribute command is still necessary.
The optional parameters in this command can be used in any combination, with the exception of the
receive-only keyword. If any of the keywords (except receive-only) is used individually, the connected
and summary routes are not sent automatically.
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Which statement is true regarding EIGRP queries? (Choose three)
A. EIGRP queries don’t need replies.
B. EIGRP queries can propagate through different ASs.
C. EIGRP queries are used to put route to SIA state.
D. Propagation of EIGRP queries can be limited with creating route summarization.
E. Propagation of EIGRP queries can be limited with creating stub routers.
Answer: B, D, E
When router loses route to a destination network and there is no feasible successor route, router floods
EIGRP query packets to its neighbors. If neighboring router has route to the destination network, replies,
if not forwards query to its neighboring router, and so on.
Problem occurs when queries propagate through whole network AS, or through another AS. Network
can’t converge until replies of the queries are not received.
Limiting range in the network where queries can propagate is important issue (less CPU and memory
usage). You can do that with configuring remote routers as stub routers, or by configuring route
summarization.
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Regarding output of the show ip protocol command, why router R1 and R2 can’t establish adjacency?
R1# show ip protocols
Routing Protocol is "eigrp 101" Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates Default networks accepted from incoming updates
EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
EIGRP maximum hopcount 100 EIGRP maximum metric variance 1
Redistributing: eigrp 101
EIGRP NSF-aware route hold timer is 240s Automatic network summarization is in effect
Maximum path: 4
Routing for Networks: 10.4.9.0/24
Routing Information Sources:
Gateway Distance Last Update 100.1.1.1 90 0:01:11
100.1.2.1 90 0:02:03
Distance: internal 90 external 170
R2# show ip protocols
Routing Protocol is "eigrp 101" Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates Default networks accepted from incoming updates
EIGRP metric weight K1=1, K2=1, K3=1, K4=0, K5=0
EIGRP maximum hopcount 200 EIGRP maximum metric variance 2
Redistributing: eigrp 11
EIGRP NSF-aware route hold timer is 240s Automatic network summarization is in effect
Maximum path: 4
Routing for Networks: 10.4.9.0/24
Routing Information Sources:
Gateway Distance Last Update 100.1.4.1 90 0:01:22
100.1.5.1 90 0:01:33
Distance: internal 90 external 170
A. K values do not match.
B. Variance values do not match.
C. Gateway IP addresses do not match.
D. AS values do not match.
E. Maximum hop counts values do not match.
Answer: A
To establish adjacency between neighboring routers must be satisfied that K values must match and AS
values must match.
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Refer to the exhibit and the output of the show ip eigrp 100 topology command on R1, which router will
be used as next hop router, R1 to send traffic to the device with IP address 192.168.100.25.
R4#sh ip eigrp 100 topology
EIGRP-IPv4 Topology Table for AS(100)/ID(198.18.34.4)
Codes: P – Passive, A – Active, U – Update, Q – Query, R – Reply,
r – reply Status, s – sia Status
P 198.18.14.0/24, 1 successors, FD is 281600
via Connected, Ethernet2
P 198.168.100.0/24, 2 successors, FD is
via 198.18.14.1 (307200/281600), Ethernet0
via 198.18.15.1 (307200/281600), Ethernet1
via 198.18.16.1 (341143/292617), Serial0
via 198.18.17.1 (370192/302010), Serial1
P 198.18.23.0/24, 1 successors, FD is 307200
via 198.18.15.1 (307200/281600), Ethernet1
A. router R2
B. router R3
C. router R4
D. router R5
E. router R3 and router R5
Answer: E
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For easier computation it is better to put all information in the table. Next table contains all information
related to get the answer of the question.
Path
Feasible
Distance (FD)
Advertised
Distance (AD)
Successor
Feasible Successor
(FS) AD(FS)<FD (S)
through R2 341143 292617 FS: 292617<307200
through R3 307200 281600 S
through R4 370192 302010 FS: 302010<307200
through R5 307200 281600 S
As we can see even we have 2 successor routers (R3 and R5 - implementation of equal load balancing)
that will be used for sending traffic to 192.168.100.25.
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Which commands can be used to limit propagation of the EIGRP queries? (Choose two)
A. router eigrp 1
B. eigrp stub
C. ip summary-address eigrp 110.1.1.1 255.255.255.0
D. redistribution eigrp
Answer: B, C
When router doesn’t have a feasible successor, floods query packets to its neighbors. If the router have
route to the destination network replies on the query, if not query is continuing propagating through the
network, until router replies on the query or there are no more routers to reply on query. Limiting
propagating queries in the network prevents consuming bandwidth, processor power and routes to become
SIA.
This can be done with creating stub routers (advertise specific routes). This is usually used in hub and
spoke scenario, where spoke routers are configured as stub routers. A stub router indicates in the hello
packet to all neighboring routers its status as a stub router. Any router that receives a packet informing it
of its neighbor’s stub status does not query the stub router for any routes. Therefore, a router that has a
stub peer does not query that peer.
Another way to limit propagation of queries in the network is using summarization. Summarization
minimizes the size of the routing table, which means less CPU and memory usage to manage it and less
bandwidth to transmit the information. Summarization also reduces the chance of networks becoming SIA
because it reduces the number of routers that see each query, so the chance of a query encountering one of
these issues is also reduced.
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Select each EIGRP command from the column on the left and drag it to its corresponding description on
the right.
Answer:
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2013 162
Refer to the exhibit. R1 and R2 use EIGRP AS1. Automatic summarization is enabled on both routers.
Which network will be advertised from R1 to R2? (Choose two)
A. 10.0.0.0/8
B. 172.18.10.0/24
C. 10.10.3.0/24
D. 192.168.10.0/24
E. 172.18.0.0/16
Answer: A, E
Because automatic summarization is enabled on both routers, routes that will be summarized to the class
boundary will be advertised. These routes are shown in the output of show ip route command on router
R2:
R2#sh ip ro
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
U - per-user static route
Gateway of last resort is not set
192.168.10.0/24 is subnetted, 1 subnets
C 192.168.10.0 is directly connected, FastEthernet0/0
D 10.0.0.0 [90/156160] via 192.168.10.1, 00:00:17, FastEthernet0/0 D 172.18.0.0 [90/156160] via 192.168.10.1, 00:00:17, FastEthernet0/0
CCNP Route 642-902 Questions/Answers - EIGRP
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Which statement is true about calculation of EIGRP metric and bandwidth usage? (Choose two)
A. Percentage of bandwidth used by EIGRP processes can’t be changed.
B. By default, EIGRP uses minimum bandwidth and total delay in calculation of the metric.
C. By default, EIGRP bandwidth usage is limited to 50 percent of the configured interface bandwidth.
D. By default, EIGRP uses minimum bandwidth, total delay, reliability, loading and MTU in calculation
of the metric.
Answer: B, C
By default, during calculation of metric EIGRP uses K values, that are related with bandwidth and delay
and other values (related with reliability, loading and MTU) are set to 0.
By default, EIGRP traffic bandwidth usage is limited to 50 percent of the configured interface bandwidth.
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Which statements are true regarding manual summarization for EIGRP?
A. Manual summarization is configured with global configuration mode command.
B. Manual summarization is configured with no auto-summary command.
C. Manual summarization is configured with router configuration mode command.
D. Manual summarization is configured with ip summary-address eigrp command.
Answer: D
To turn off automatic summarization, use the no auto-summary router configuration command.
Use the ip summary-address eigrp as-number address mask [admin-distance] interface configuration
command to manually create a summary route at an arbitrary bit boundary, as long as a more specific
route exists in the routing table.
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Refer to the exhibit. You have to configure EIGRP in your company network. All router interfaces are
operational and all IP addresses are configured. You have to: configure EIGRP for routers R1, R2, R3 and
R4 using EIGRP AS 10; configure EIGRP to advertise subnetworks that are configured on each interface;
and all routes need to be not summarized.
R1: networks 100.1.1.0/24; 100.1.2.0/24; and 100.1.3.0/24;
R2: networks 100.1.1.0/24; 100.2.2.0/24; and 10.1.1.0/24;
R3: networks 101.1.1.0/24; 101.1.2.0/24; and 10.1.1.0/24;
R4: networks 101.1.1.0/24; 101.2.2.0/24; and 101.2.3.0/24;
Answer:
For router R1 configuration is as follows:
R1(config)#router eigrp 10
R1(config-router)#network 100.1.1.0 0.0.0.255
R1(config-router)#network 100.1.2.0 0.0.0.255
R1(config-router)#network 100.1.3.0 0.0.0.255
R1(config-router)#no auto-summary
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;
For router R2 configuration is as follows:
R2(config)#router eigrp 10
R2(config-router)#network 100.1.1.0 0.0.0.255
R2(config-router)#network 100.2.2.0 0.0.0.255
R2(config-router)#network 10.1.1.0 0.0.0.255
R2(config-router)#no auto-summary
;
For router R3 configuration is as follows:
R3(config)#router eigrp 10
R3(config-router)#network 101.1.1.0 0.0.0.255
R3(config-router)#network 101.1.2.0 0.0.0.255
R3(config-router)#network 10.1.1.0 0.0.0.255
R3(config-router)#no auto-summary
;
For router R4 configuration is as follows:
R4(config)#router eigrp 10
R4(config-router)#network 101.1.1.0 0.0.0.255
R4(config-router)#network 101.2.2.0 0.0.0.255
R4(config-router)#network 101.2.3.0 0.0.0.255
R4(config-router)#no auto-summary
;
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Which routes can be found in the EIGRP routing table?
A. Successor
B. Feasible successors
C. All routes
D. Successor and feasible successor
Answer: A
EIGRP routing table contains just successors, which are the best next-hop routers to a destination.
EIGRP topology table contains successors and feasible successors. Feasible successors are neighboring
routers that have loop-free path to the destination.
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Which code describes default route in the output of the show ip route command?
A. EX
B. S
C. *
D. D
Answer: C
* - in the output of the show ip route command indicates that the route is the default route.
D*EX 0.0.0.0/0 – indicates default route that is redistributed into EIGRP.
D EX – indicates external EIGRP route, that is redistributed into EIGRP.
D – indicates internal EIGRP route.
S – indicates static route, created with ip route command.
S* - indicates static default route.
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Refer to the exhibit. All routers are configured with EIGRP, with default summarization settings. Each
router is configured to advertise directly connected networks. You have issued on R1 and R2 following
command:
router eigrp 11
no auto-summary
Which output lines from show ip route command will be given?
A.
10.0.0.0/24 is subnetted, 1 subnets
D 10.1.1.0 [90/156160] via 192.168.44.1, 00:00:17, FastEthernet0/0
192.168.44.0/24 is subnetted, 1 subnets
C 192.168.44.0 is directly connected, FastEthernet0/0
C 192.168.1.0 is directly connected, FastEthernet0/1 D 172.18.0.0/16 [90/178126] via 192.168.44.1, 00:00:19, FastEthernet0/0
B.
10.0.0.0/24 is subnetted, 1 subnets
D 10.1.1.0 [90/156160] via 192.168.44.1, 00:00:17, FastEthernet0/0 192.168.44.0/24 is subnetted, 1 subnets
C 192.168.44.0 is directly connected, FastEthernet0/0
C 192.168.1.0 is directly connected, FastEthernet0/1 172.18.0.0/24 is subnetted, 1 subnets
D 172.18.1.0/16 [90/178126] via 192.168.44.1, 00:00:19, FastEthernet0/0
C. 10.0.0.0/24 is subnetted, 1 subnets
D 10.1.1.0 [90/156160] via 192.168.44.1, 00:00:17, FastEthernet0/0
D 172.18.0.0/16 [90/178126] via 192.168.44.1, 00:00:19, FastEthernet0/0
D. 192.168.44.0/24 is variably subnetted, 2 subnets, 2 masks
D 192.168.44.0/24 is a summary, 00:00:17, Null0
C 192.168.44.0 is directly connected, FastEthernet0/0 C 192.168.1.0 is directly connected, FastEthernet0/1
Answer: A
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Because we have issued no-auto summary on routers R1 and R2 automatic summarization is disabled on
them. But, on R3 automatic summarization is enabled, so router R3 will advertise summarized route to
router R2, which advertises to router R1.
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You have configured router in Branch office, to gain connectivity to the Main office router, as follows:
router eigrp 11
network 10.1.10.0
network 172.17.1.0 redistribute connected
redistribute static
auto-summary eigrp stub
Which routes will Branch router advertise to the Main office router?
A. static routes and summary routes
B. static routes and directly connected routes
C. static routes and routes redistributed from other protocols
D. directly connected routes and summary routes
E. directly connected routes and routes redistributed from other protocols
Answer: D
Command eigrp stub configures router as stub router. This means that only summary routes and directly
connected routes are advertised by default.
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Refer to the exhibit. You have issued variance 2 command on the router R1. How many routes will router
R1 use to route traffic t0 the network 10.10.1.0/24?
A. one
B. two
C. tree
D. four
Answer: A
For easier computation it is better to put all information in the table. Next table contains all information
related to get the answer of the question.
Path
Feasible
Distance (FD)
Advertised
Distance (AD)
Successor
Feasible Successor
(FS) AD(FS)<FD (S)
Unequal Load Balancing
Path
(variance 2)
FD(Feasible)<2*FD (S)
through R2 130 100
through R3 200 120
through R4 200 80 FS: 80<100
through R5 100 40 S S
As we can see even we have included variance value 2 (implementation of unequal load balancing) just
successor router (next-hop router) will be used for sending traffic to network 10.10.1.0/24.
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Select the packet types from the left and drag them under the appropriate technology on the right. Some
descriptors may be used more than once.
Answer:
EIGRP uses the following five types of packets:
• Hello - Hello packets are used for neighbor discovery. They are sent as multicasts and do not
require an acknowledgment. (They carry an acknowledgment number of 0.)
• Update - Update packets contain route change information. An update is sent to communicate the
routes that a particular router has used to converge. An update is sent only to affected routers.
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Update packets are sent as multicasts when a new route is discovered, and when convergence is
complete (in other words, when a route becomes passive). To synchronize topology tables, update
packets are sent as unicasts to neighbors during their EIGRP startup sequence. Update packets are
sent reliably.
• Query - When a router is performing route computation and does not have an FS, it sends a query
packet to its neighbors, asking whether they have a successor to the destination. Queries are normally
multicast but can be retransmitted as unicast packets in certain cases. They are sent reliably.
• Reply - A reply packet is sent in response to a query packet. Replies are unicast to the originator of
the query and are sent reliably. A router must reply to all queries.
• ACK - The ACK is used to acknowledge updates, queries, and replies. ACK packets are unicast
hello packets and contain a nonzero acknowledgment number. (Note that hello and ACK packets do
not require acknowledgment.)
OSPF Packets are shown below:
1 Hello - Discovers neighbors and builds adjacencies between them
2 Database description (DBD) - Checks for database synchronization between routers
3 Link-state request (LSR) - Requests specific link-state records from another router
4 LSU - Sends specifically requested link-state records
5 LSAck - Acknowledges the other packet types
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Which statement is true regarding EIGRP manual summarization?
A. Manual configuration is done in interface configuration mode.
B. Manual configuration is done in global configuration mode.
C. Manual configuration is performed with command no auto-summary
D. Manual configuration is performed with command no auto-summary address eigrp
Answer: A
To enable manual summarization in EIGRP, you have to use command ip summary-address eigrp as-
number ip-address mask [admin-distance] in interface configuration mode.
More on: Link1
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2013 176
From the column on the right select each parameter for the eigrp stub command and drag it to the
appropriate column on the right.
Answer:
eigrp stub command uses following parameters:
- receive-only – configures the router to receive routes but not advertise routes
- connected – configures the router to advertise directly connected networks
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- redistributed – configures the router to advertise routes learned from another protocol
- static – configures the router to advertise static routes
- summary – configures the router to advertise summary routes
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2013 178
In regard of the show ip protocols command, which methods are used by the router Main to calculate
EIGRP composite metric? (Choose two)
Main#show ip protocols
Routing Protocol is "eigrp 100"
Outgoing update filter list for all interfaces is not set Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
EIGRP maximum hopcount 100
EIGRP maximum metric variance 1
Redistributing: eigrp 100
EIGRP NSF-aware route hold timer is 240s
Automatic network summarization is not in effect Maximum path: 4
Routing for Networks:
2.2.2.2/32 10.1.1.2/32
10.2.2.2/32
Routing Information Sources: Gateway Distance Last Update
10.2.2.3 90 00:55:44
10.1.1.1 90 00:55:44 Distance: internal 90 external 170
A. load
B. reliability
C. delay
D. bandwidth
Answer: C, D
As we can see from show ip protocols command:
EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
In case when K5 is 0 (by default) EIGRP metric is calculated using following formula:
metric=(K1 x bandwidth) + [(K2 x bandwidth)/(256-load)] + (K3 x delay)
, because K1=1, K2=0 and K3=1we have:
metric= bandwidth + delay
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Which command is used to create manual summary route to the network 192.168.1.0/24 for Main router
that is configured for EIGRP AS 3?
A. Main(config-if)#ip summary-address eigrp 3 192.168.1.0 0.0.0.255
B. Main(config-router)#ip summary-address eigrp 3 192.168.1.0 0.0.0.255
C. Main(config)#ip summary-address eigrp 3 192.168.1.0 0.0.0.255
D. Main(config-router)#ip summary-address eigrp 3 192.168.1.0 255.255.255.0
E. Main(config-if)#ip summary-address eigrp 3 192.168.1.0 255.255.255.0
Answer: E
To enable manual summarization in EIGRP, you have to use command ip summary-address eigrp as-
number ip-address mask [admin-distance] in interface configuration mode.
More on: Link1
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Regarding partial output of the show ip eigrp topology command, which of the following routes will be
displayed in the output of the show ip route command?
P 172.16.90.0/24, 2 successors, FD is 0 via 172.16.80.28 (46251776/46226176), Ethernet0
via 172.16.81.28 (46251776/46226176), Ethernet1
via 172.16.80.31 (46277376/46251776), Serial0
A. D 172.16.90.0/24 [90/46251776] via 172.16.80.28, 01:08:11, Ethernet0
B. D 172.16.90.0/24 [90/46251776] via 172.16.81.28, 01:08:11, Ethernet1
C. D 172.16.90.0/24 [90/46277376] via 172.16.80.31, 01:08:11, Serial0
D. D 172.16.90.0/24 [90/46251776] via 172.16.80.28, 01:08:11, Ethernet0
D 172.16.90.0/24 [90/46277376] via 172.16.80.31, 01:08:11, Serial0
E. D 172.16.90.0/24 [90/46251776] via 172.16.80.28, 01:08:11, Ethernet0
D 172.16.90.0/24 [90/46251776] via 172.16.81.28, 01:08:11, Ethernet1
Answer: E
By default just best route to the destination network will be placed in the EIGRP routing table.
If multiple routes have same metrics, up to 4 routes will be placed in the routing table and load balance
will be used to send traffic to the destination network.
In our case we have two routes with same FD, that will be successor routes, and both will be placed into
routing table, as shown below (marked with red):
P 172.16.90.0/24, 2 successors, FD is 0 via 172.16.80.28 (46251776/46226176), Ethernet0
via 172.16.81.28 (46251776/46226176), Ethernet1
via 172.16.80.31 (46277376/46251776), Serial0
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All routers are configured to use EIGRP. You have to configure: router R2 to manually summarize routes
into 192.168.1.64/24 network, which it receives from router R3 on Fa0/0 interface and to ensure that
router R3 will suppress outbound EIGRP hellos on Serial0 interface.
Answer:
You have to use following commands:
R1(config)#interface FastEthernet0/0
R1(config-if)#ip summary-address eigrp 10 192.168.1.64 255.255.255.0
and:
R3(config)#router eigrp 10
R3(config-router)#passive-interface serial 0
- passive-interface command prevents neighbor relationship to be established over a passive interface,
stops routing updates from being processed or sent over passive interface and allows a subnet on a passive
interface to be announced in an EIGRP process.
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Which administrative distance is assigned to EIGRP summary routes by default?
A. 0
B. 1
C. 5
D. 90
E. 170
Answer: C
To EIGRP summary routes it is assigned administrative distance (AD) of 5 by default. Router with lower
AD will be preferred over the route with higher AD. Following table contain commonly used AD:
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Which statement is true regarding EIGRP queries? (Choose two)
A. Propagation of EIGRP queries can be stopped using stub routers.
B. Propagation of EIGRP queries can be stopped using route summarization.
C. Router doesn’t need reply for sent EIGRP queries.
D. EIGRP queries prevents router to become SIA.
Answer: A, B
EIGRP query propagation into network reduces incidences with SIA. To limit EIGRP query propagation
through the network, you can use route summarization or to configure remote routers as stub EIGRP
routers.
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Refer to the exhibit and given outputs from show commands below. All routers are configured with
EIGRP.
Router# show ip eigrp topology
IP-EIGRP Topology Table for process 77
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - Reply status
P 172.16.81.0 255.255.255.0, 1 successors, FD is 307200
via Connected, Ethernet1 via 172.16.81.28 (307200/281600), FastEthernet0/0
via 172.16.80.28 (332800/307200), FastEthernet0/1
Router# show ip route
Codes: I - IGRP derived, R - RIP derived, O - OSPF derived,
C - connected, S - static, E - EGP derived, B - BGP derived,
* - candidate default route, IA - OSPF inter area route, i - IS-IS derived, ia - IS-IS, U - per-user static route,
o - on-demand routing, M - mobile, P - periodic downloaded static route,
D - EIGRP, EX - EIGRP external, E1 - OSPF external type 1 route, E2 - OSPF external type 2 route, N1 - OSPF NSSA external type 1 route,
N2 - OSPF NSSA external type 2 route
Gateway of last resort is not set
D 172.16.81.0 [90/307200] via 172.16.81.28, 00:01:23, FastEthernet0/0
Why route to network 172.16.81.0/24 through router R4 is not listed in the routing table? (Choose two)
A. EIGRP doesn’t support unequal load balancing.
B. variance is set to 3
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C. variance is set to 1
D. FD of R2 is lower than FD of R4
E. FD of R2 is higher than FD of R4
Answer: C, D
In our case in routing table we have route through successor router (Router R2). That means that variance
is set to 1. If variance is set to 3 then route through router R4 will also be in the routing table.
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Which of the following is displayed in the output of the show ip eigrp interfaces command?
A. Number of directly connected EIGRP neighbors.
B. IP address of directly connected EIGRP neighbors.
C. FD to the network connected on the interface
D. Automatic network summarization is in place.
Answer: A
Typical output from show ip eigrp interfaces command is shown below:
Router# show ip eigrp interfaces
IP EIGRP interfaces for process 109
Xmit Queue Mean Pacing Time Multicast Pending
Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes Di0 0 0/0 0 11/434 0 0
Et0 1 0/0 337 0/10 0 0
SE0:1.16 1 0/0 10 1/63 103 0 Tu0 1 0/0 330 0/16 0 0
Number of directly connected neighbors is shown into Peers column (marked with red).
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All routers are configured with EIGRP, with automatic summarization enabled. On which router you
should issue no-auto summary command?
A. On all routers
B. On router R1
C. On router R2
D. On router R3
E. On router R3 and router R5
Answer: E
You have to use no auto-summary command on router R3 and router R5, when a classful network is
divided and portions of the same classful network exist in different parts of the network topology. We
can see that router R3 and router R5 are configured with different parts of the 10.0.0.0/8 Class A address
space. Because automatic summarization is enabled, routers R3 and R5 will advertise 10.0.0.0/8 summary
route to router R4. Problem can occur because if both routes have same costs router R4 will load balance
and can send traffic to the wrong router, or if both routes have different costs then router R4 will use route
with lowest cost and will prevent sending traffic through the highest cost route, to the other router.
CCNP Route 642-902 Questions/Answers - EIGRP
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Select the values from the left that need not match each other in an EIGRP network in order for a router to
establish adjacencies with its neighbors.
Answer:
K values and AS number values must match between EIGRP routers adjacency to be formed.
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Refer to the output of the show command below:
RouterX# show ip eigrp topology
IP-EIGRP Topology Table for AS(100)/ID(192.168.1.65)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 10.1.1.0/24, 1 successors, FD is 40514560
via 10.140.1.1 (40514560/28160), Serial0/0/0
P 10.2.2.0/24, 1 successors, FD is 28160
via Connected, FastEthernet0/0
P 10.3.3.0/24, 1 successors, FD is 40514560
via 10.23.23.2 (40514560/28160), Serial0/0/1
P 10.23.23.0/24, 1 successors, FD is 40512000
via Connected, Serial0/0/1
P 192.168.1.64/28, 1 successors, FD is 128256
via Connected, Loopback0
P 192.168.1.0/24, 1 successors, FD is 40640000
via 10.23.23.2 (40640000/128256), Serial0/0/1
P 10.140.2.0/24, 2 successors, FD is 41024000
via 10.23.23.2 (41024000/40512000), Serial0/0/1
via 10.140.1.1 (41024000/40512000), Serial0/0/0
via 11.140.1.1 (41034000/40522000), Serial0/0/2
P 10.140.1.0/24, 1 successors, FD is 40512000
via Connected, Serial0/0/0
P 172.16.31.0/24, 1 successors, FD is 40640000
What should you do to enable load balancing through all links to network 10.140.2.0/24?
A. Issue variance 1 command on RouterX.
B. Issue variance 2 command on RouterX.
C. Issue router eigrp 7 command on RouterX.
D. Issue metric weights 0 1 0 0 1 7 command on RouterX.
Answer: B
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For easier computation it is better to put all information in the table. Next table contains all information
related to get the answer of the question.
Path Feasible Distance
(FD)
Advertised Distance
(AD)
Successor
Feasible Successor (FS)
AD(FS)<FD (S)
Unequal Load Balancing
Path (variance 2)
FD(Feasible)<2*FD (S)
via 10.23.23.2 41024000 40512000 S
via 10.140.1.1 41024000 40512000 S
via 11.140.1.1 41034000 40522000 FS: 40522000<41024000 41034000<2*41024000
As we can see even we have included variance value 2 (implementation of unequal load balancing) and
feasible router (11.140.1.1) will also be used for sending traffic to network 10.140.2.0/24.
Command metric weights 0 1 0 0 1 7 adjust K values, which EIGRP uses to calculate FD and AD.
Modifying K values can cause undesired effect on the network. Recommendation by Cisco is using
default settings. K values msut match neighbor adjacencies to be established.
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Router Main got 2 successor routes in the routing table. Which packet will be send to the neighboring
routers, when cost of the routes will be changed?
A. unicast hello
B. multicast hello
C. unicast reply
D. multicast query
E. multicast update
Answer: E
Multicast update is sent to 224.0.0.10, when changes that affect modification of network topology or cost
to reach the destination.
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Packets addressed to which of the following multicast addresses are received by all EIGRP routers on the
segment?
A. 224.0.0.1
B. 224.0.0.2
C. 224.0.0.5
D. 224.0.0.6
E. 224.0.0.9
F. 224.0.0.10
Answer: F
In the table below are shown well-known IPv4 addresses that are reserved for IP multicasting and that are
registered with the IANA (Internet Assigned Numbers Authority).
More on: Link1
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Refer to the exhibit and show ip route partial output below, which statement is true? (Choose three)
D 10.0.0.0/8 [90/2562718] via 192.168.55.1/24, 00:01:11, FastEthernet0/0 192.168.55.0/24 is subnetted, 1 subnets
C 192.168.55.0/30 is directly connected, FastEthernet0/0
C 192.168.2.0/30 is directly connected, FastEthernet0/1 172.19.0.0/24 is subnetted, 1 subnets
D 172.19.1.0 [90/2727212] via 192.168.55.1/24, 00:01:09, FastEthernet0/0
A. Automatic summarization is enabled on router R1.
B. Automatic summarization is disabled on router R1.
C. Automatic summarization is enabled on router R2.
D. Automatic summarization is disabled on router R2.
E. Automatic summarization is enabled on router R3.
F. Automatic summarization is disabled on router R3.
Answer: B, C, F
Automatic summarization is enabled on router R2 and disabled on routers R1 and R3. Router R2 is
directly connected to networks 10.11.1.0/24 and 192.168.55.0/24. Network 192.168.55.0/24 is directly
connected to router R1 also. R1 learns about network 10.11.1.0/24 from router R2. We can see that route
summarization is enabled on router R2, because we have route that is summarized to /8 bit boundary. If
automatic summarization was disabled on the router R2 then, in the R1 routing table we would have
following statements:
10.0.0.0/24 is subnetted, 1 subnets D 10.11.1.0 [90/2562718] via 192.168.55.1/24, 00:01:11, FastEthernet0/0
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After implementing EIGRP on your network, you issue the show ip eigrp traffic command on router C.
The following output is shown:
RouterC#show ip eigrp traffic
IP-EIGRP Traffic Statistics for process 1
Hellos sent/received: 2112/2076
Updates sent/received: 47/38 Queries sent/received: 5/3
Replies sent/received: 3/4
Acks sent/received: 29/33 Input queue high water mark 2, 0 drops
SIA-Queries sent/received: 0/0
SIA-Replies sent/received: 0/0
Moments later, you issue the same command a second time and the following output is shown:
RouterC#show ip eigrp traffic
IP-EIGRP Traffic Statistics for process 1 Hellos sent/received: 2139/2104
Updates sent/received: 50/39
Queries sent/received: 5/4 Replies sent/received: 4/4
Acks ent/received: 31/37
Input queue high water mark 2, 0 drops SIA-Queries sent/received: 0/0
SIA-Replies sent/received: 0/0
Moments later, you issue the same command a third time and the following output is shown:
RouterC#show ip eigrp traffic
IP-EIGRP Traffic Statistics for process 1
Hellos sent/received: 2162/2126
Updates sent/received: 53/42 Queries sent/received: 5/5
Replies sent/received: 5/4
Acks sent/received: 35/41 Input queue high water mark 2, 0 drops
SIA-Queries sent/received: 0/0
SIA-Replies sent/received: 0/0
What information can you determine about this network?
A. The network is stable.
B. There is a flapping link or interface, and router C knows an alternate path to the network.
C. There is a flapping link or interface, and router C does not know an alternate path to the network.
D. EIGRP is not working correctly on router C.
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E. There is not enough information to make a determination.
Answer: B
The show ip eigrp traffic command summarizes the number of hello packets router receives and
sends. show ip eigrp traffic command show how many updates, queries, replies, and acknowledges router
uses to ensure that EIGRP is running correctly and there are exchanges with adjacent EIGRP routers.
If we look in the query statement in show ip eigrp traffic command, we can see that 5 queries are sent and
just 1 received. That means there is no Feasible Successor for some route in the routing table, for which
Successor is not available any more. Router will start sending queries to find alternative route to the
destination network, for which this route exist in topology table as Active route.
Until all 5 queries are not received route will be Active, but network topology is stable and there is no
network changes, except that active route is unavailable for present router.
When all queries are received then new Successor is determined and new route will be put into routing
table.
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A network administrator is troubleshooting and EIGRP connection between router A IP address 10.1.2.1
and routerB IP address 10.1.2.2. Given the debug output on RouterA, which two statements are true?
RouterA#debug eigrp packets
…
01:39:13: EIGRP: Received HELLO on Serial0/0 nbr 10.1.2.2 01:39:13: AS 100, Flags 0x0, Seq 0/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
01:39:13: K-value mismatch
A. RouterA received a hello packet with mismatched autonomous systems numbers
B. RouterA received a hello packet with mismatched hello timers
C. RouterA received a hello packet with mismatched authentication parameters
D. RouterA received a hello packet with mismatched metric-calculation mechanisms
E. RouterA will form an adjacency with router B
F. RouterA will not form an adjacency with router B
Answer: D, F
Because there is k-value mismatch between the EIGRP neighboring routers, neighbor relationships ain’t
gonna be formed.