600 quality questions for your ccna studies

The Bryant Advantage® 600 Quality Questions

For Your CCNA© Studies

Chris Bryant, CCIE™ # 12933

www.thebryantadvantage.com

Copyright Information: Cisco®, Cisco® Systems, CCNA™, and Cisco Certified Internetwork Expert are registered trademarks of Cisco® Systems, Inc., and/or its affiliates in the U.S. and certain countries. All other products and company names are the trademarks, registered trademarks, and service marks of the respective owners. Throughout this Course Guide, The Bryant Advantage has used its best efforts to distinguish proprietary trademarks from descriptive names by following the capitalization styles used by the manufacturer. Disclaimer: This publication, The Bryant Advantage: 600 Quality Questions For Your CCNA Exam Studies, , is designed and intended to assist candidates in preparation for the CCNA exams for the Cisco Certified Network Associate ® certification. All efforts have been made by the author to make this book as accurate and complete as possible, but no guarantee, warranty, or fitness are implied, expressly or implicitly. The enclosed material is presented on an “as is” basis. Neither the author, Bryant Instructional Services, or the parent company assume any liability or responsibility to any person or entity with respect to loss or damages incurred from the information contained in this workbook. This ebook is an original work by the Author. Any similarities between materials presented in this Study Guide and actual CCNA® exam questions are completely coincidental. Copyright 2004 © The Bryant Advantage

Section One: Internetworking Models Questions What is a broadcast domain? A broadcast domain is the set of hosts and network devices that will receive all broadcasts sent on a network segment. Using CSMA/CD, a node does what before sending traffic? Using Carrier Sense Multiple Access with Collision Detection, the node will first listen to the wire before sending traffic. If two nodes send a packet at the same time and they collide, what happens next? The nodes wait a random amount of time and then retransmit. What’s the main difference between how switches and routers handle broadcasts? Switches will forward broadcasts, but routers won’t. Of hubs, switches, repeaters, and bridges, which devices are typically used to break up a collision domain? Switches and bridges break up collision domains. What device regenerates an electrical signal, allowing it to travel further than it could on its own? A repeater.

Chris Bryant, CCIE #12933 www.thebryantadvantage.com © 2004 The Bryant Advantage

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Of hubs, routers, switches, repeaters, and bridges, which is typically used to break up a broadcast domain? Routers break up broadcast domains. What is the uppermost layer of the OSI model? The Application layer. Name four main purposes of the Application layer. The Application layer ensures the remote partner is available; that the needed resources for this communication are available; and that both sides of the communication agree on data integrity procedures. Authentication also occurs at this layer. Name three main purposes of the Presentation layer. Operating system compatibility, proper data encapsulation for network transmission, and data formatting. What layer handles the building and teardown of the connection between the two end points? The Session layer handles building and tearing down the connection. Name three main purposes of the Transport layer. Data flow controls, error checking mechanisms, and the reliable arrival of messages. When the Transport layer uses a connection-oriented method of transporting data, what protocol is it using? TCP is connection-oriented. When the Transport layer uses a connectionless method of transporting data, what protocol is it using?


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UDP is connectionless. What is the term for the part of router memory that holds packets that are awaiting processing? The buffer. What term refers to the synchronization and acknowledgement process two parties go through when building a TCP connection? This is the “three-way handshake”. What is “windowing”? Windowing is used in TCP. It refers to the sender not waiting for an acknowledgement from the receiver for every single packet before sending more packets. In the OSI model, what layer is often referred to as “Layer 3”? The Network layer. At what layer of the OSI model does switching take place? Layer 2, the Data Link layer. At what layer of the OSI model does routing take place? Layer 3, the Network layer. Of IP, OSPF, EIGRP, and RIP, which is a routed protocol? IP is a routed protocol.


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What’s the difference between a routed protocol and a routing protocol? A routing protocol discovers and exchanges routes; the routed protocol are just what they sound like; they’re the protocols that get routed. What layer concerns itself with IP addresses? The Network layer. What layer concerns itself with MAC addresses? The Data Link layer. Of binary, decimal, and hexadecimal, what type of numbering scheme are MAC addresses expressed in? MAC addresses are expressed in hexadecimal. What layer is sometimes referred to as “the bit level”? The Physical layer. The electrical and physical specifications for moving data are set at what level? The Physical layer. Which layer concerns itself with file, print, database, application, and message services? The Application layer.


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What layer uses port numbers to keep data from different applications separate? The Session layer. How many layers make up the Cisco hierarchical model? Three. Name the layers of the Cisco hierarchical model, from the innermost to the outermost. Core, Distribution, Access. Under what circumstances will a host on an Ethernet segment send a “jam signal”? A host that is currently transmitting packets will send a jam signal to another host on the same segment that attempts to being transmission. What type of cable is used to connect two switches? A crossover cable. What type of cable is used to connect a router to a switch? A straight-through cable. What type of cable is used to connect a host directly to the COM port of a router? A rolled cable. At what layers of the OSI model is data referred to as “data”? The top three layers – Application, Presentation, and Session. At what layer of the OSI model is data referred to as “packets”?


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The Network layer. At what layer of the OSI model is data referred to as “frames”? The Data Link layer. At what layer of the OSI model is data referred to as “data segments” or “segments”? The Transport layer. What is the purpose of the Address Resolution Protocol? ARP is used when the Layer 3 address of a remote device is known, but the Layer 2 address is not. What protocol can a diskless workstation use to obtain its IP address when it knows its MAC address? A diskless workstation in this situation will use RARP – Reverse Address Resolution Protocol. True or False: When CSMA/CD is in effect, a host will send a jam signal prior to transmitting data. False; A host only sends a jam signal if it is transmitting and another host on the wire attempts to transmit at the same time. True or False: At the Presentation layer, data is referred to as “packets”. False. At the Presentation level, data is referred to as “data”. “Packets” are found at the Network layer. True or False: Authentication is typically handled at the Application layer.


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True. As the Application layer is the uppermost layer, and the layer that the end user has actual input with, it makes sense that any prompts for authentication would have to come at this layer. True or False: The Session layer uses IP addresses to keep different data streams separate. False. The Session layer uses port numbers to keep different data streams separate. True or False: The most appropriate devices to use to break up a collision domain are switches and bridges. Answer: True. True or False: In a network, a regenerator is used to strenghten an electical signal, giving it greater range. Answer: False. This is performed by a repeater. True or False: The uppermost layer of the OSI model is the Physical layer. Answer: False. The Physical layer is the bottom layer. The Application layer is the top layer. True or False: TCP is considered connection-oriented, and UDP is considered connectionless. Answer: True. True or False: TCP does not necessarily wait for an "ack" from the receiver for every single packet before the sender transmits more packets. Answer: True. This is referred to as "windowing". True or False: A router is considered a Layer 3 device.


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Answer: True. Routers work at the Network layer, which in the OSI model is Layer Three. True or False: A cable is considered a Layer 1 device. Answer: True. While a cable is not usually thought of as a "device", it does run at Layer 1. True or False: OSPF is a routed protocol. Answer: False: OSPF is a routing protocol, becuause it discovers routes. IP is a routed protocol. True or False: The Cisco hierarchical model closely mirrors the OSI model. Answer: False. The Cisco hierarchical model is a three-layer model referencing layers of a campus network; the OSI model is a seven-layer model illustrating data transfer processes. True or False: When connecting a host directly to the COM port of a router, you should use a rolled cable. Answer: True. True or False: When connecting a switch to a router, use a crossover cable. Answer: False. A switch-router connection calls for a straight-through cable.


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Section Two: LAN Switching Questions When a switch receives a frame, does it look at the source MAC address, the destination MAC address, or both? Both. The switch looks at the source MAC first to see if an entry needs to be made into the MAC address table, then at the destination MAC to see how to handle the frame. If the source MAC is known but the destination is not, how does the switch handle the frame? The switch floods the frame with the unknown destination out all ports except the one on which it was received. If the destination MAC address is known, is the frame then multicasted, broadcasted, or unicasted? The frame is unicast. Under what circumstances does a switch filter a frame? A frame is filtered when the MAC table indicates that the destination MAC address for this frame is found off the same port as the source MAC address, meaning that the source and destination are on the same network segment. A switch receives a frame to be broadcasted. Out what ports is this frame sent? The frame is sent out every port except the one on which it was received. What is the MAC address of a broadcast? The MAC address is FFFF.FFFF.FFFF.

Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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© 2004 The Bryant Advantage

Describe the three modes of Cisco switch port security. Protect mode drops packets with unknown source addresses once the limit of secure MAC addresses is reached. Restrict does the same thing, and it sends a syslog message as well. Shutdown is the default; the port LED goes out and the interface enters err-disabled state. What is the main purpose of Spanning Tree Protocol? STP is used for loop prevention on Cisco switches. Ports along the most-desirable path are put into forwarding mode, and ports on less-desirable parts are put into blocking mode. What type of frame or packet is used by Cisco switches to carry out the root bridge election? BPDUs – Bridge Protocol Data Units – carry the information needed to carry out the election. True or False: The lowest BID wins the root bridge election. True. What two values make up the Bridge ID (BID)? The BID is made up of the bridge’s priority and MAC address. The priority is the front part of the BID, while the MAC is the second part. Three switches are vying to be the root bridge of VLAN 10. One has a priority of 4196; one has a priority of 8294; the other has the default priority. Which will become the root bridge? The switch with the lowest priority becomes the root bridge. The default priority will be the highest of the three.


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What one-line command would make a switch the root bridge of VLAN 150, regardless of what priority has been set on the other switches in the vlan? Spanning-tree vlan 150 root priority Concerning root bridge election, what assumption does a switch make when it boots up for the first time on a network? The switch assumes it is the root bridge of all VLANs until a root bridge election tells it otherwise. What is a designated bridge? What is a designated port? A designated bridge is the bridge on a network segment with the lowest cost to the root bridge. The designated bridge’s port through which it reaches the root bridge is the designated port. By default, how often do switches send out BPDU Hellos? BPDU Hellos are sent out every two seconds. What is the purpose of the MaxAge value in a BPDU? The MaxAge tells the bridge how long it should wait after not hearing a Hello BPDU before attempting to change the STP topology. What is the purpose of the ForwardDelay value in a BPDU? The ForwardDelay value indicates how long a port should stay in the listening and learning stages. What Cisco feature allows a port to skip the listening and learning stages of Spanning Tree? Portfast allows a port to skip the listening and learning stages.


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What term refers to the ability of VLAN traffic to flow over interconnected switches in the same network? Trunking. What is the default VLAN? VLAN 1 is the default VLAN. What can a VTP Server do that a VTP Client cannot? A VTP server can create, modify, and delete VLANs. A VTP Client cannot. How does VTP Transparent mode handle VTP messages? Switches running VTP Transparent mode will forward VTP messages, but will not actually accept them. What VTP feature prevents the unnecessary transmission of broadcasts and multicasts across a trunk link? VTP Pruning prevents broadcasts and multicasts from going across the trunk link unless they’re necessary for VLANs on the remote switch. What is a broadcast storm? A broadcast storm occurs when segments receive broadcasts and respond with broadcasts of their own. The number of broadcasts continues to grow, preventing transmission of unicasts and multicasts. What kind of switch port belongs to one VLAN and will carry only that VLAN’s traffic? An access port belongs to only one VLAN.


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What is the default trunking mode of a Cisco 2950 switch port? The default trunking mode is dynamic desirable, meaning that the port will actively try to create a trunk with the remotely connected port. What term refers to the logical bundling of multiple physical connections between two Cisco switches? EtherChannels combine multiple physical connections into one logical connection. Three physical connections exist between two switches. How does STP view these connections after they are put into one EtherChannel? STP views an EtherChannel as a single port, regardless of how many physical connections actually make up the EtherChannel. What command will display the devices directly connected to a Cisco switch? Show cdp neighbor What two commands will put a port into Vlan 23, and ensure the port cannot become a trunk port? Switchport mode access Switchport access vlan 23 In VLAN database mode, what command will change the name of vlan 546 to “Engineering”? vlan 546 name Engineering What is the default priority of a Cisco switch?


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32768 What port-level command places a switch port into Portfast? spanning portfast What command will display the root bridge and STP timer values of VLAN 24? Show spanning-tree vlan 24 What command will display the VLAN trunking protocol domain name, password, and whether pruning is enabled? Show vtp status You are exiting vlan database mode with < CTRL – Z>. What effect does this particular method have? VLAN database changes are not saved when you exit with <CTRL – Z>. Use exit to leave vlan database mode and save changes. How do you view the bridging table of a Cisco 2950 switch? The MAC address table, often referred to as the “bridging table”, is displayed with show mac-address-table. When VTP is enabled on a switch, what is the default mode? Is it Server, Client, or Transparent? VTP Server is the default VTP mode.


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What command produced the following console readout? SW2# VTP Version : 2 Configuration Revision : 1 Maximum VLANs supported locally : 1005 Number of existing VLANs : 5 VTP Operating Mode : Client VTP Domain Name : CCNA VTP Pruning Mode : Enabled Show vtp status You want to interconnect two Cisco 2950 switches. What kind of cable will you need? Crossover cables are used to interconnect Cisco switches. What command produced the following console readout? SW1# VLAN0023 Spanning tree enabled protocol ieee Root ID Priority 32791 Address 0009.b738.9180 This bridge is the root Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32791 (priority 32768 sys-id-ext 23) Address 0009.b738.9180 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 300 Show spanning-tree vlan 23


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What command produced the following console output? SW2# Secure Port MaxSecureAddr CurrentAddr SecurityViolation Security Action (Count) (Count) (Count) --------------------------------------------------------------------------- Fa0/3 1 1 0 Shutdown Show port-security Concerning port security on a Cisco switch, what is the main difference between a dynamic secure address and a sticky secure address? Both are dynamically learned, but the sticky secure address is retained after a reboot. Dynamic secure addresses are lost on reboot and must be relearned. How does ISL handle the native VLAN? ISL doesn’t recognize native VLANs. 44 questions. True or False: When VLANs are configured on a Cisco switch, broadcasts between VLANs are still forwarded to ensure connectivity between VLANs. Answer: False. One benefit of VLANs is limiting broadcasts. True or False: If a frame’s destination is known, the frame is sent only to that destination, and is said to be “unicast”. Answer: True. If the frame’s destination is known, there’s no need to flood the frame.


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True or False: MAC addresses are expressed in binary format. Answer: False. MAC addresses are expressed in hexadecimal. True or False: Multicasts have a MAC address of FFFF.FFFF.FFFF. ANSWER: False. Broadcasts have a MAC address of FFFF.FFFF.FFFF. True or False: When a port is in Shutdown mode, and it is shut down due to a security violation, the port will be reenabled after 15 minutes. ANSWER: False. The port must be manually reenabled. Your network has a EtherChannel made up of four physical connections. One of the four connections goes down due to a faulty cable. What impact does this have on STP? None. STP will see the EtherChannel as one single connection, not four separate ones. If one of the physical connections goes down, STP has no reason to recalculate, since STP will still see the single logical connection. STP doesn’t care how many physical connections make the port-channel up. You are doing some routine checking on your 2950 switch and notice a port called “port-channel 1”. What kind of port is this? The “port-channel” is the logical port created when an EtherChannel is created. 51 questions. You have several physical connections between two of your Cisco switches. When checking spanning tree statistics, you notice none of the physical port numbers are showing, but you do see an interface called “Po1”. What is this interface?


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That’s short for “port-channel”, the logical port created when an EtherChannel is created. True or False: ISL doesn’t use native VLANs, but dot1q does. True. Name two methods of limiting broadcasts on a Cisco 2950 switch. VTP Pruning limits broadcasts across a trunk line; creating VLANs limits broadcasts between hosts on the same switch. What is the maximum number of physical ports that can be placed into an EtherChannel? Eight physical ports can be placed into a single EtherChannel. A switch has a priority of 32768 and a MAC address of aaaa.aaaa.aaaa. What does its BID look like? The switch’s Bridge ID will be 32768:aaaa.aaaa.aaaa. True or False: Switches forward broadcasts out all ports. False. Switches forward broadcasts out all ports except the one upon which it was received. Switch A is participating in a root bridge election for vlan 1. That switch receives a BPDU from Switch B that contains a higher BID than the one the switch is sending out. What action will Switch A take? Switch A will continue to send BPDUs announcing itself as the root bridge. The lowest BID will become the root bridge. Switch A is participating in a root bridge election for vlan 1. That switch receives a BPDU from Switch B that contains a lower BID than the one Switch A is sending out. What action will Switch A take?


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Switch A will continue to send BPDUs, but these BPDUs will now recognize Switch B as the root bridge. True or False: Portfast is appropriate for use on a port connected to a switch or router. False. Portfast should only be used on a port connecting to an end-user device. Using portfast on a port connected to another switch or a router can lead to routing loops. True or False: It’s acceptable to have a five-switch VTP domain where all five switches are VTP Servers. True. There doesn’t have to be a client in a VTP domain to be a valid domain.


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Section Three: Frame Relay Questions What interface-level command is used to enable Frame Relay? Encapsulation frame-relay What interface-level command is used to disable Inverse ARP? No frame-relay inverse-arp What term is given to the logical connection through a path of DCEs used in Frame Relay to describe the path between two DTEs? This path is referred to as a Frame Relay cloud. In Frame Relay, what is the Committed Information Rate? The CIR is the amount of bandwidth guaranteed to a client by the frame relay service provider. In Frame Relay, what is the difference between a PVC and an SVC? A PVC (Permanent Virtual Circuit) is available at all times; an SVC (Switched Virtual Circuit) is available only when certain criteria are met. What term is used for a Frame Relay topology where every router has a logical connection to every other router? This is a full-mesh network. In a typical Frame Relay network, what device is the DCE? The DCE is a device in the service provider’s network. In a typical Frame Relay network, what device is the DTE? The DTE is a Cisco router in the local network.


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What is the purpose of the Frame Relay LMI? The Frame Relay LMI (Local Management Interface) serves as a keepalive for the connection between the DCE (the service provider) and the DTE (the Cisco router). What are the three types of Frame Relay LMI? What is the default? Ansi, Cisco, and q933a. Cisco is the default. What Cisco feature makes it unnecessary to manually configure LMI types? LMI Autosense. When LMI Autosense is enabled, how many LMI Status messages does the DTE send? How many does the DCE return? The DTE will send three LMI Status messages – one of each LMI type (ansi, q933a, cisco). The DCE will return only one, the LMI type it’s configured to use. Does the Frame Relay encapsulation type have to match between the DTE and DCE, or between DTEs only? The Frame Relay encap type has to match between DTEs. The DCE does not care about the encapsulation type. What are the two Frame Relay encapsulation types? Cisco and ietf. Cisco is the default. In Frame Relay, what does DLCI stand for? Data-Link Connection Identifier.


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Do DLCIs have global significance or local significance? DLCIs have local significance only; that is, the same DLCI number can be used on different access links in the same network. What term is given to the DLCI numbering scheme where a router in the Frame Relay network is reached via the same DLCI number from each router in the network? This is referred to as “global addressing”. It does not affect the fact that DLCIs have local significance only. You want to use static mappings in your Frame Relay configuration, and you want no dynamic mappings to occur. What single command will prevent dynamic mappings? On the Frame Relay interfaces, configure no frame-relay inverse-arp. Looking at this router console readout, what protocol mapped these Frame Relay DLCIs? R1#show frame map Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), dynamic, broadcast,, status defined, active Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), dynamic, broadcast,, status defined, active These Frame Relay mappings were mapped by Inverse ARP. Looking at this Frame Relay configuration, how must mapping now be configured? R1(config)#interface serial0 R1(config)#ip address 172.12.123.1 255.255.255.0 R1(config-if)#encapsulation frame-relay R1(config-if)#no frame-relay inverse-arp The statement “no frame-relay inverse-arp” prevents dynamic mappings. Static mappings will now have to be configured with the frame map statement.


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You have a point-to-point serial subinterface running Frame Relay. You will use DLCI 687 to reach the other end of the link. What is the appropriate command to use on the subinterface? On the subinterface, run frame-relay interface-dlci 687. There is no need for a mapping statement, since frames leaving this interface have only one possible destination – it’s a point-to-point interface. You want to change interface Serial0’s LMI type from cisco to ansi. What is the appropriate command? On Serial0, run frame-relay lmi-type ansi. After running show frame pvc, you notice that you’re receiving a large amount frames with the FECN bit set. What does this indicate? The FECN (Forward Express Congestion Notification) bit indicates that congestion was experienced in the direction the frame was traveling. After running show frame pvc, you notice that you’re receiving a large amount of Frame Relay headers with the BECN bit set. What does this indicate? The BECN (Backward Explicit Congestion Notification) bit indicates that congestion was experienced in the opposite direction from which the frame was traveling. You suspect an LMI mismatch in your Frame Relay network. What is the first command to run? Show frame lmi will not only show you the LMIs that have been received, but the number of timeouts, which may indicate the line has gone down or is about to do so.


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What command will show you the LMI type being sent by the remote DCE? Debug frame lmi will show you the incoming LMI type. You realize that someone has changed the LMI type of your router’s Serial0 interface away from the default. What command sets the LMI type back to the default? Under the interface configuration for Serial0, configure frame lmi-type cisco. True or False: The term "frame relay cloud" refers to a logical connection between two DTEs that travels through a path of DCEs. Answer: True. True or False: The term "switched virtual circuit" refers to a Frame Relay connection that is only up under certain circumstances. Answer: True. SVCs are temporary, PVCs are permanent. True or False: The dynamic creation of PVCs cannot be prevented. Answer: False. With the command "no frame-relay inverse-arp" configured on the interface, the dynamic creation of PVCs is stopped. True or False: In a typical Frame Relay network, the DTE is the end user. Answer: False. The DTE is generally a router, where the DCE is a device in the service provider's network. True or False: The three types of Frame Relay LMI are ansi, cisco, and q933a, with ansi being the default. Answer: False. Those are the three types of Frame Relay LMI, but cisco is the default.


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True or False: The DLCI used on different Cisco routers to reach the same destination must be the same. Answer: False. DLCIs have local significance only.


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Section Four: ISDN Questions What command allows you to view CHAP and PAP authentication taking place? Debug ppp negotiation If two Cisco routers are directly connected via Serial interfaces, what must the DCE router do? The router acting as the DCE must supply a clock rate. What command indicates what traffic is considered “interesting traffic”? Dialer-list What command is used on the BRI interface to link the dialer-list to the interface? Dialer-group What command displays whether the cable connected to a Serial interface is the DTE end or DCE end? Show controller What command displays the source and destination of traffic that brought up an ISDN line? Show dialer What is the default encapsulation type for a Serial point-to-point link? HDLC. What interface-level command will change the default encapsulation type on a Serial point-to-point link to PPP?


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Encapsulation ppp What PPP authentication scheme sends the password over the wire in clear-text? PAP sends passwords in clear-text. What does PAP stand for? Password Authentication Protocol. Can the passwords sent by the two hosts in a PAP authentication scheme be different? With PAP, the passwords can be different. With CHAP, they cannot. How does CHAP handle sending the password? CHAP runs a hash algorithm using the password and a random number. This hash result is sent. Can the passwords sent by the two hosts in a CHAP authentication scheme be different? No. Since the hash result must match on both sides, the passwords used in running the hash must be the same. What is the primary purpose of a B-channel in ISDN? B-channels carry data. What is the primary purpose of a D-channel in ISDN? D-channels set up and tear down the call. How many B-channels and D-channels are there in an ISDN BRI? Two B-channels and one D-channel. What is the capacity of a D-channel in an ISDN BRI?


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16 kbps. In a United States PRI, how many B-channels and D-channels are there? There are 23 B-channels and one D-channel. What is the capacity of a D-channel in a United States PRI? 64 kbps. What ISDN command verifies that the switch-type has been defined and the SPIDs are valid? Show isdn status What is the term for the packets that will cause a router to dial another router and bring up the ISDN link? Interesting traffic. By default, once the ISDN link is up, what traffic can go across it? Any traffic, not just interesting traffic. What value determines when the ISDN link goes down? The idle-timer. What kind of traffic resets the ISDN idle-timer? Interesting traffic not only brings the ISDN link up, it also resets the ISDN idle-timer. What is the default value for the ISDN idle-timer? 120 seconds.


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What command does a dialer profile use to indicate the number to dial to reach the remote router? Dialer string What command will tell you if there’s an active call on your ISDN link? Show isdn status What command will show you all calls placed on a router over the last 15 minutes? Show isdn history By default, will broadcasts go out over an ISDN link? No. The “broadcast” keyword must be used in the dialer map statement for this to happen. What two interface-level commands would be necessary to enable PPP PAP authentication on an ISDN interface? Encapsulation ppp Ppp authentication pap What command is needed for a PAP authentication scheme that is never used in CHAP? Ppp pap sent-username must be used in a PAP authentication scheme. PPP is running on your ISDN routers. What two commands will bring the second B-channel up when the first B-channel reaches 50% of capacity? Ppp multilink


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Dialer load-threshold 127 Remember that the value expressed with “dialer load-threshold” is a ratio of 255, not 100. When using dialer profiles, what command links the physical interface to the logical interface? Dialer pool-member In dotted decimal, what is the most appropriate subnet mask to use on a point-to-point ISDN link? 255.255.255.252. This allows two usable host addresses, one for each end of the link. No addresses are wasted. What command is required for an ISDN connection, since this command defines the ISDN switch type? Isdn switch-type What protocol defines the D-channel’s call setup and call teardown messages? Q.931 What ISDN command defines a valid incoming dial number when call screening is in effect? Isdn caller What is the purpose of the ISDN command “dialer fast-idle”? Dialer fast-idle defines how long the router will wait to timeout existing lines when other interesting traffic is waiting for that line. It’s basically an accelerator for the idle-timeout value. What are the two framing types available with PRI? SF and ESF.


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In the command “dialer-list 2 protocol ip list 101”, what is the “101” referring to? The extended access-list that is defining interesting traffic. Basic-5ess, vn3, and basic-ni1 are types of what? They’re three different ISDN switch types. What command resulted in this console output? R1# HD unit 1, idb = 0x107114, driver structure at 0x10C590 buffer size 1524 HD unit 1, V.35 DTE cable show controller serial 0 The interface name can’t be derived from the output, but that is the full command. Serial1 is a DCE interface directly connected to a DTE. The line is not up by default. What command was added to bring the line up? R3(config)#int serial 1 R3(config-if)# %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, changed state to up The command clockrate 56000 was added. (The rate isn’t important; 56000 or 64000 would be fine. Knowing the DCE has to supply clockrate to the DTE is the important concept.) You have a point-to-point link. One side is running HDLC encapsulation; the other side is running PPP. Is the physical interface down, the line protocol down, or is the line up? An encapsulation mismatch will result in the line protocol being down.


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What is achieved with the following configuration? R1#conf t R1(config)#dialer-list 1 protocol ip permit R1(config)#int bri0 R1(config-if)#dialer-group 1 This configuration defines all IP traffic as interesting traffic, meaning that any IP traffic will cause the line to dial. What command resulted in this console output? R1#s Layer 1 Status: ACTIVE Layer 2 Status: TEI = 98, Ces = 1, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED TEI = 99, Ces = 2, SAPI = 0, State = MULTIPLE_FRAME_ESTABLISHED Spid Status: TEI 98, ces = 1, state = 5(init) spid1 configured, no LDN, spid1 sent, spid1 valid TEI 99, ces = 2, state = 5(init) spid2 configured, no LDN, spid2 sent, spid2 valid Show isdn status What command resulted in this console output? R1# Call Calling Called Remote Seconds Seconds Seconds Charges Type Number .Number Name Used Left Idle Units/Currency ----------------------------------------------------------------------------------------------------------- Out 8358662 R2 121 0 Out 8358662 R2 121 0 Show isdn history What command resulted in this console output? R2#show dialer


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BRI0 - dialer type = ISDN Dial String Successes Failures Last called Last status 8358661 2 0 00:00:04 successful 0 incoming call(s) have been screened. BRI0:1 - dialer type = ISDN Idle timer (120 secs), Fast idle timer (20 secs) Wait for carrier (30 secs), Re-enable (15 secs) Dialer state is data link layer up Dial reason: ip (s=172.12.21.2, d=172.12.21.1) Time until disconnect 117 secs Connected to 8358661 (R1) Show dialer What command resulted in this console output? 22:12:07: %LINK-3-UPDOWN: Interface BRI0:1, changed state to up 22:12:07: %DIALER-6-BIND: Interface BRI0:1 bound to profile Dialer1 22:12:07: %ISDN-6-CONNECT: Interface BRI0:1 is now connected to 8358662 22:12:07: BR0:1 PPP: Phase is AUTHENTICATING, by both 22:12:07: BR0:1 CHAP: O CHALLENGE id 3 len 23 from "R1" 22:12:07: BR0:1 CHAP: I CHALLENGE id 3 len 23 from "R2" 22:12:07: BR0:1 CHAP: O RESPONSE id 3 len 23 from "R1" 22:12:07: BR0:1 CHAP: I SUCCESS id 3 len 4 22:12:07: BR0:1 CHAP: I RESPONSE id 3 len 23 from "R2" 22:12:07: BR0:1 CHAP: O SUCCESS id 3 len 4 22:12:07: BR0:1 PPP: Phase is UP debug ppp negotiation When configuring a dialer profile, does the IP address go on the physical or the logical interface? The IP address will be placed on the logical interface. Use no ip address to remove the address from the physical interface if one is present. When configuring a dialer profile, are the SPIDs placed on the physical or the logical interface?


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The SPIDs are always placed on the physical interface. You notice your ISDN link is staying up well after you think it should be down. “show dialer” indicates packets with a destination address of 224.0.0.5 are keeping the line up. What protocol is keeping the line up? What command remedies this, if any? A destination address of 224.0.0.5 indicates that OSPF packets are keeping the line up. Configure ip ospf demand-circuit under the BRI interface on one side of the link to prevent this. True or False: When configuring the clockrate command for directly connected Serial interfaces, the command always goes on the DTE. False. The clockrate is always configured on the DCE. True or False: Configuring CHAP allows you to use different passwords for each router in the ISDN connection. False. PAP allows you to use different passwords; CHAP requires use of the same password. Describe what CHAP does with a password during the authentication process. The CHAP password is hashed, along with a random number. It is this hash result that is sent to the remote router. True or False: Regardless of whether the line is PRI or BRI, U.S. or International, there is still only one D-channel in an ISDN link. True. The capacity changes, as BRI D-channels have 16 kbps capacity and PRI D-channels have 64 kbps, but there’s still only one.


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Put these three values in order, lowest to highest. The number of B-channels in a PRI(US); the number of B-channels in a BRI; the number of B-channels in a PRI (Europe). The number of B-channels in a BRI: 2 The number of B-channels in a PRI (US): 23 The number of B-channels in a PRI (Europe): 30 What will this command do? Conf? This usage of IOS Help will show all commands available in the current mode that begin with “conf”. When using “show interface bri0” on your ISDN router, you notice the interface shows as “administratively down”. What will resolve this issue? “administratively down” means someone shut the interface down. Reopen it with “no shutdown” on the interface level. The value entered with the ISDN command dialer load-threshold reflects a ratio of what number? This value is a ratio of 255. That is, for the link to come up at 50% capacity, you would enter “dialer load-threshold 127”.


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Section Five: Binary Math Questions What is the default network mask for a Class A network? 255.0.0.0, or /8. What is the default network mask for a Class B network? 255.255.0.0, or /16. What is the default network mask for a Class C network? 255.255.255.0, or /24. The Class A network address 26.1.1.1 has how many network bits and how many host bits? Class A networks have 8 network bits and 24 host bits. The Class B network address 145.5.5.5 has how many network bits and how many host bits? Class B networks have 16 network bits and 16 host bits. The Class C network address 210.1.1.1 has how many network bits and how many host bits? Class C networks have 24 network bits and 8 host bits. When subnetting is performed, are the subnet bits “borrowed” from the network bits or the host bits? Subnetting always borrows bits from the host bits. The network portion of the address does not change. What is the primary reason for subnetting? Subnetting’s primary purpose is conservation of IP addresses.


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What formula is used to determine the number of valid subnets for a given network number and mask? Use this formula: The number of subnets = (2 squared by the number of subnet bits) – 2 Written in binary, what is the default network mask for a Class B network? In binary, that’s 11111111 11111111 00000000 00000000. Expressed in prefix notation, what is the equivalent of 255.255.240.0? Prefix notation is simply a slash followed by the number of 1s in the subnet mask. In binary, this mask would be 11111111 11111111 11110000 00000000; in prefix notation, it’s /20 (pronounced “slash twenty”). In the following formula, why is two subtracted at the end? The number of subnets = (2 squared by the number of subnet bits) – 2 Two subnets are subtracted; the all-zeroes subnet (“subnet zero”) and the all-ones subnet (the broadcast subnet). When calculating the number of valid hosts on a subnet, what formula is used? Number Of Valid Hosts On A Subnet = (2 squared by number of host bits) – 2 In the following formula, why is two subtracted at the end? Number Of Valid Hosts On A Subnet = (2 squared by number of host bits) – 2 Two addresses are subtracted. The address with all zeroes for host bits is the subnet number itself; the address with all ones for host bits is the broadcast address for that subnet. Neither address should be used for hosts.


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How is the mask 255.128.0.0 expressed in prefix notation? The first 9 bits of this mask are “1”, so in prefix notation, this mask is expressed as /9. How is the mask 255.255.192.0 expressed in prefix notation? The first 18 bits of this mask are “1”, so in prefix notation, this mask is expressed as /18. How is the mask 255.255.255.252 expressed in prefix notation? The first 30 bits of this mask are “1”, so in prefix notation, this mask is expressed as /30. This is a common mask for point-to-point links. How is the mask 255.254.0.0 expressed in prefix notation? The first 13 bits of this mask are “1”, so in prefix notation, this mask is expressed as /13. How is the mask 255.255.255.255 expressed in prefix notation? All 32 bits of this mask are “1”, so in prefix notation, this mask is expressed as /32. How is the address 194.34.85.200 expressed in binary?

128 64 32 16 8 4 2 1 194 1 0 0 0 0 0 1 0 34 0 0 1 0 0 0 1 0 85 0 1 0 1 0 1 0 1 200 1 1 0 0 1 0 0 0

The binary expression is 10000010 00100010 01010101 11001000.


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How is the address 75.120.42.68 expressed in binary?

128 64 32 16 8 4 2 175 0 1 0 0 1 0 1 1120 0 1 1 1 1 0 0 042 0 0 1 0 1 0 1 068 0 1 0 0 0 1 0 0

The binary expression is 01001011 01111000 00101010 01000100. How is the address 219.39.245.89 expressed in binary?

128 64 32 16 8 4 2 1219 1 1 0 1 1 0 1 139 0 0 1 0 0 1 1 1245 1 1 1 1 0 1 0 189 0 1 0 1 1 0 0 1


128 64 32 16 8 4 2 123 0 0 0 1 0 1 1 112 0 0 0 0 1 1 0 0204 1 1 0 0 1 0 1 1254 1 1 1 1 1 1 1 0

The binary expression is 00010111 00001100 11001011 11111110. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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How is the address 47.231.23.49 expressed in binary?

128 64 32 16 8 4 2 147 0 0 1 0 1 1 1 1231 1 1 1 0 0 1 1 123 0 0 0 1 0 1 1 149 0 0 1 1 0 0 0 1


128 64 32 16 8 4 2 1245 1 1 1 1 0 1 0 1227 1 1 1 0 0 0 1 145 0 0 1 0 1 1 0 1235 1 1 1 0 1 0 1 1

The binary expression is 11110101 11100011 00101101 11101011. You’re working with the network 172.18.0.0. You have determined you will need 24 subnets. What is the appropriate subnet mask? The number of subnets = (2 squared by the number of subnet bits) – 2 For 24 subnets, you’ll need 5 subnet bits, which gives you 30 valid subnets. The default mask for this network is 255.255.0.0. Borrow five host bits for subnetting and you have a subnet mask of 255.255.248.0. You’re working with the network 10.0.0.0. You have determined you will need 46 subnets. What is the appropriate subnet mask? The number of subnets = (2 squared by the number of subnet bits) – 2 For 46 subnets, you’ll need 6 subnet bits, which gives you 62 valid subnets. The default mask for this network is 255.0.0.0. Borrow six host bits for subnetting and you have a subnet mask of 255.252.0.0.


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You’re working with the network 212.18.234.0. You have determined you will need seven subnets. What is the appropriate subnet mask? The number of subnets = (2 squared by the number of subnet bits) – 2 For seven subnets, you’ll need 4 subnet bits, which gives you 14 valid subnets. (Three subnet bits gives you only six valid subnets.) The default mask for this network is 255.255.255.0. Borrow four host bits for subnetting and you have a subnet mask of 255.255.255.240. You’re working with the network 78.0.0.0. You have determined you will need 164 subnets. What is the appropriate subnet mask? The number of subnets = (2 squared by the number of subnet bits) – 2 For 164 subnets, you’ll need 8 subnet bits, resulting in 254 valid subnets. The default network mask is 255.0.0.0. Borrow eight host bits for subnetting and you have a subnet mask of 255.255.0.0. What is the dotted decimal equivalent of the following binary number? 01110001 00111100 01110101 11110010 Simply use this chart and add the bit values containing a “1”, from left to right.

128 64 32 16 8 4 2 1 DecimalValue

0 1 1 1 0 0 0 1 113 0 0 1 1 1 1 0 0 60 0 1 1 0 0 1 0 1 101 1 1 1 1 0 0 1 0 242

The dotted decimal equivalent is 113.60.101.242.


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What is the dotted decimal equivalent of the following binary number? 11001001 01000101 01000111 001111111 Simply use this chart and add the bit values containing a “1”, from left to right.

128 64 32 16 8 4 2 1 DecimalValue

1 1 0 0 1 0 0 1 201 0 1 0 0 0 1 0 1 69 0 1 0 0 0 1 1 1 71 0 0 1 1 1 1 1 1 63

The dotted decimal equivalent is 201.69.71.63. What is the dotted decimal equivalent of the following binary number? 11111110 01010011 11111100 01001010 Simply use this chart and add the bit values containing a “1”, from left to right.

128 64 32 16 8 4 2 1 DecimalValue

1 1 1 1 1 1 1 0 254 0 1 0 1 0 0 1 1 83 1 1 1 1 1 1 0 0 252 0 1 0 0 1 0 1 0 74

The dotted decimal equivalent is 254.83.252.74. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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128 64 32 16 8 4 2 1 DecimalValue

1 1 0 0 0 1 0 1 197 0 0 1 1 0 0 1 1 51 1 1 0 0 1 1 1 1 207 0 0 1 1 1 1 0 0 60


128 64 32 16 8 4 2 1 DecimalValue

1 1 1 1 1 0 0 0 248 0 0 0 0 1 1 1 1 15 0 1 0 0 0 1 0 1 67 1 1 1 1 1 0 0 1 249


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128 64 32 16 8 4 2 1 DecimalValue

1 1 0 0 1 0 1 0 202 1 1 1 1 0 0 0 0 240 0 0 0 0 1 1 1 1 15 0 0 0 0 0 0 0 1 1

The dotted decimal equivalent is 202.240.15.1 What is the dotted decimal equivalent of the following binary number? 11100000 00000111 01000101 00010010 Simply use this chart and add the bit values containing a “1”, from left to right.

128 64 32 16 8 4 2 1 DecimalValue

1 1 1 0 0 0 0 0 224 0 0 0 0 0 1 1 1 7 0 1 0 0 0 1 0 1 69 0 0 0 1 0 0 1 0 18


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128 64 32 16 8 4 2 1 DecimalValue

1 1 0 0 0 1 0 1 197 1 1 0 0 0 1 1 1 199 0 0 1 1 1 0 0 0 56 0 0 0 0 0 0 0 0 0


128 64 32 16 8 4 2 1 DecimalValue

0 0 0 0 0 0 1 1 3 0 0 1 0 0 0 1 0 34 0 1 1 0 1 1 1 1 111 1 1 1 1 1 1 0 0 252


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128 64 32 16 8 4 2 1 DecimalValue

0 0 1 1 1 1 1 1 63 0 0 1 0 0 1 0 1 37 1 1 1 1 1 1 1 1 255 0 0 0 1 0 1 0 0 20

The dotted decimal equivalent is 63.37.255.20. What is the dotted decimal equivalent of this binary number? 00000100 00101010 11000010 00100101 Simply use this chart and add the bit values containing a “1”, from left to right.

128 64 32 16 8 4 2 1 DecimalValue

0 0 0 0 0 1 0 0 4 0 0 1 0 1 0 1 0 44 1 1 0 0 0 0 1 0 194 0 0 1 0 0 1 0 1 41


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What is the dotted decimal equivalent of this binary number? 11110011 00111111 11000100 00111111 Simply use this chart and add the bit values containing a “1”, from left to right.

128 64 32 16 8 4 2 1 DecimalValue

1 1 1 1 0 0 1 1 243 0 0 1 1 1 1 1 1 63 1 1 0 0 0 1 0 0 196 0 0 1 1 1 1 1 0 62

The dotted decimal equivalent is 243.63.196.62. How is the dotted decimal address 100.10.1.145 expressed in binary?

128 64 32 16 8 4 2 1100 0 1 1 0 0 1 0 010 0 0 0 0 1 0 1 01 0 0 0 0 0 0 0 1145 1 0 0 1 0 0 0 1

The binary equivalent is 01100100 00001010 00000001 10010001. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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How is the dotted decimal address 245.39.145.29 expressed in binary?

128 64 32 16 8 4 2 1245 1 1 1 1 0 1 0 139 0 0 1 0 0 1 1 1145 1 0 0 1 0 0 0 129 0 0 0 1 1 1 0 1

The address in binary is 11110101 00100111 10010001 00011101. How is the dotted decimal address 45.190.234.18 expressed in binary?

128 64 32 16 8 4 2 145 0 0 1 0 1 1 0 1190 1 0 1 1 1 1 1 0234 1 1 1 0 1 0 1 018 0 0 0 1 0 0 1 0


128 64 32 16 8 4 2 1251 1 1 1 1 1 0 1 110 0 0 0 0 1 0 1 01 0 0 0 0 0 0 0 1245 1 1 1 1 0 1 0 1

The address in binary is 11111011 00001010 00000001 11110101. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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How is the dotted decimal address 10.235.231.97 expressed in binary?

128 64 32 16 8 4 2 110 0 0 0 0 1 0 1 0235 1 1 1 0 1 0 1 1231 1 1 1 0 0 1 1 197 0 1 1 0 0 0 0 1


128 64 32 16 8 4 2 1199 1 1 0 0 0 1 1 1230 1 1 1 0 0 1 1 017 0 0 0 1 0 0 0 1248 1 1 1 1 1 0 0 0


128 64 32 16 8 4 2 1245 1 1 1 1 0 1 0 1100 0 1 1 0 0 1 0 0139 1 0 0 0 1 0 1 184 0 1 0 1 0 1 0 0

The address in binary is 11110101 01100100 10001011 01010100. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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What is the binary equivalent of the dotted decimal IP address 190.87.23.254?

128 64 32 16 8 4 2 1190 1 0 1 1 1 1 1 087 0 1 0 1 0 1 1 123 0 0 0 1 0 1 1 1254 1 1 1 1 1 1 1 0

The binary equivalent is 10111110 01010111 00010111 11111110. What is the binary equivalent of the dotted decimal IP address 201.48.199.89?

128 64 32 16 8 4 2 1201 1 1 0 0 1 0 0 148 0 0 1 1 0 0 0 0199 1 1 0 0 0 1 1 189 0 1 0 1 1 0 0 1

The binary equivalent is 11001001 00110000 11000111 01011001. What is the dotted decimal equivalent of the dotted decimal IP address 23.198.49.205?

128 64 32 16 8 4 2 123 0 0 0 1 0 1 1 1198 1 1 0 0 0 1 1 049 0 0 1 1 0 0 0 1205 1 1 0 0 1 1 0 1

The binary equivalent is 00010111 11000110 00110001 11001101. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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How many valid subnets exist on the 10.0.0.0 /11 network? Default Mask 255.0.0.0 11111111 00000000 0000000 00000000 Subnet Mask 255.224.0.0 11111111 11100000 0000000 00000000

There are three subnet bits, where the default mask has a zero and the subnet mask has a one. 2 to the 3rd power is 8; subtract 2 from that, and you have 6 valid subnets left. How many valid subnets exist on the 200.45.45.0 /27 network? Default Mask 255.255.255.0 11111111 11111111 11111111 00000000 Subnet Mask 255.255.255.224 11111111 11111111 11111111 11100000 There are three subnet bits, where the default mask has a zero and the subnet mask has a one. 2 to the 3rd power is 8; subtract 2 from that, and you have 6 valid subnets left. How many valid subnets exist on the 190.45.45.0 /25 network? Default Mask 255.255.0.0 11111111 11111111 00000000 00000000 Subnet Mask 255.255.255.128 11111111 11111111 11111111 10000000 There are 9 subnet bits, where the default mask has a zero and the subnet mask has a one. 2 to the 9th power is 512; subtract 2 from that, and you have 510 valid subnets left. How many valid subnets exist in the 200.10.10.0 /29 network? Default Mask 255.255.255.0 11111111 11111111 11111111 00000000 Subnet Mask 255.255.255.248 11111111 11111111 11111111 11111000 There are 5 subnet bits, where the default mask has a zero and the subnet mask has a one. 2 to the 5th power is 32; subtract 2 from that, and you have 30 valid subnets left.


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How many valid subnets exist in the 20.0.0.0 /14 network? Default Mask 255.0.0.0 11111111 00000000 0000000 00000000 Subnet Mask 255.252.0.0 11111111 11111100 0000000 00000000 There are 6 subnet bits, where the default mask has a zero and the subnet mask has a one. 2 to the 6th power is 64; subtract 2 from that, and you have 62 valid subnets left. How many valid subnets exist in the 156.15.0.0 /27 network? Default Mask 255.255.0.0 11111111 11111111 00000000 00000000 Subnet Mask 255.255.255.224 11111111 11111111 11111111 11100000 There are 11 subnet bits, where the default mask has a zero and the subnet mask has a one. 2 to the 11th power is 2048; subtract 2 from that, and you have 2046 valid subnets left. How many valid subnets exist in the 193.10.1.0 /30 network? Default Mask 255.255.255.0 11111111 11111111 11111111 00000000 Subnet Mask 255.255.255.252 11111111 11111111 11111111 11111100 There are 6 subnet bits, where the default mask has a zero and the subnet mask has a one. 2 to the 6th power is 64; subtract 2 from that, and you have 62 valid subnets left. 59 questions. How many valid hosts are there in the 200.10.1.0 /27 subnet? Default Mask 255.255.255.0 11111111 11111111 11111111 00000000 Subnet Mask 255.255.255.224 11111111 11111111 11111111 11100000 There are five host bits, where both the default mask and subnet mask have a zero. 2 to the 5th power is 32; subtract 2 from that, and you have 30 valid hosts.


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How many valid hosts are there in the 150.10.0.0 /20 subnet? Default Mask 255.255.0.0 11111111 11111111 00000000 00000000 Subnet Mask 255.255.240.0 11111111 11111111 11110000 00000000 There are 12 host bits, where both the default mask and subnet mask have a zero. 2 to the 12th power is 4196; subtract 2 and you have 4194 valid hosts. How many valid hosts are there in the 47.0.0.0 /28 subnet? Default Mask 255.0.0.0 11111111 00000000 00000000 00000000 Subnet Mask 255.255.255.240 11111111 11111111 11111111 11110000 There are 4 host bits, where both the default mask and subnet mask have a zero. 2 to the 4th power is 16; subtract 2 and you have 14 valid hosts. How many valid hosts are there in the 245.17.89.0 /29 subnet? Default Mask 255.255.255.0 11111111 11111111 11111111 11111000 Subnet Mask 255.255.255.248 11111111 11111111 11111111 11111000 There are 3 host bits, where both the default mask and subnet mask have a zero. 2 to the 3rd power is 8; subtract 2 and you have 6 valid hosts. 63 questions. How many valid hosts are there in the 235.23.12.0 /30 subnet? Default Mask 255.255.255.0 11111111 11111111 11111111 11111100Subnet Mask 255.255.255.2452 11111111 11111111 11111111 11111100 There are 2 host bits, where both the default mask and subnet mask have a zero. 2 to the 2nd power is 4; subtract 2 and you have 2 valid hosts.


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Is a subnet mask of 255.255.255.254 valid? No. This would leave only one host bit, which would result in no valid host addresses. Is a subnet mask of 255.255.254.0 valid? Yes. The presence of a “254” in the subnet mask doesn’t mean the mask cannot be used, unless the 254 is the final octet of the mask (255.255.255.254). Given an IP address and its subnet mask, how do you determine the subnet the address can be found on? Convert the address and the mask to binary. Perform a Boolean AND. Convert the Boolean AND result to dotted decimal. This yields the subnet the IP address can be found on. On what subnet does the IP address 200.1.1.20 /28 reside on? Convert the address and mask to binary. Perform a Boolean AND. Address 11001000 00000001 00000001 00010100Mask 11111111 11111111 11111111 11110000Boolean AND 11001000 00000001 00000001 00010000Boolean In Decimal 200 1 1 16 The subnet is 200.1.1.16 /28. On what subnet does the IP address 217.39.58.200 /25 reside? Convert the address and mask to binary. Perform a Boolean AND. Address 11011001 00100111 00111010 11001000Mask 11111111 11111111 11111111 10000000Boolean AND 11011001 00100111 00111010 10000000Boolean In Decimal 217 39 58 128


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The subnet is 217.39.58.128 /25. On what subnet does the IP address 143.29.14.118 / 22 reside? Address 10001111 00011101 00001110 01110110Mask 11111111 11111111 11111100 00000000Boolean AND 10001111 00011101 00001100 00000000Boolean In Decimal 143 29 12 0 The subnet is 143.29.12.0 /22. On what subnet does the IP address 209.48.200.200 /26 reside? Address 11010001 00110000 11001000 11001000Mask 11111111 11111111 11111111 11000000Boolean AND 11010001 00110000 11001000 11000000Boolean In Decimal 209 48 200 192 The subnet is 209.48.200.192 /26. On what subnet does the IP address 100.1.1.6 /30 reside? Address 00001010 00000001 00000001 00000110Mask 11111111 11111111 11111111 11111100Boolean AND 00001010 00000001 00000001 00000100Boolean In Decimal 10 1 1 4 The subnet is 100.1.1.4 /30. On what subnet does the IP address 123.56.78.126 /23 reside? Address 01111011 00111000 01001110 01111110Mask 11111111 11111111 11111110 00000000Boolean AND 01111011 00111000 01001110 00000000Boolean In Decimal 123 56 78 0 Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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The subnet is 123.56.78.0 /23. On what subnet does the IP address 248.234.10.27 /28 reside? Address 11111000 11101010 00001010 00011011Mask 11111111 11111111 11111111 11110000Boolean AND 11111000 11101010 00001010 00010000Boolean In Decimal 248 234 10 16 The subnet is 248.234.10.16 /28. What is the broadcast address for the subnet 200.100.10.16 /28? Subnet Address 11001000 01100100 00001010 00010000Subnet Mask 11111111 11111111 11111111 11110000Set Host Bits Of Subnet Address To 1. This is the broadcast.

11001000 01100100 00001010 00011111

Broadcast, Decimal 200 100 10 31 The broadcast address for this subnet is 200.100.10.31. What is the broadcast address for the subnet 100.1.14.32 /27 ? Subnet Address 01100100 00000001 00001110 00100000Subnet Mask 11111111 11111111 11111111 11100000Set Host Bits Of Subnet Address To 1. This is the broadcast.

01100100 00000001 00001110 00111111

Broadcast, Decimal 100 1 14 63 The broadcast address for this subnet is 100.1.14.63. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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What is the broadcast address for the subnet 56.10.200.8 /30? Subnet Address 00111000 00001010 11001000 00001000Subnet Mask 11111111 11111111 11111111 11111100Set Host Bits Of Subnet Address To 1. This is the broadcast.

00111000 00001010 11001000 00001011

Broadcast, Decimal 56 10 200 11 The broadcast address for this subnet is 56.10.200.11. 77 questions. What is the broadcast address for the subnet 109.83.23.128 /26? Subnet Address 01101101 01010011 00010111 10000000Subnet Mask 11111111 11111111 11111111 11000000Set Host Bits Of Subnet Address To 1. This is the broadcast.

01101101 01010011 00010111 10111111

Broadcast, Decimal 109 83 23 191 The broadcast address is 109.83.23.191. What is the broadcast address for the subnet 90.87.18.0 /23? Subnet Address 01011010 01010111 00010010 00000000Subnet Mask 11111111 11111111 11111110 00000000Set Host Bits Of Subnet Address To 1. This is the broadcast.

01011010 01010111 00010011 11111111

Broadcast, Decimal 90 87 19 255 The broadcast address is 90.87.19.255. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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What is the broadcast address for the subnet 199.90.200.96 /27? Subnet Address 11000111 01011010 11001000 01100000Subnet Mask 11111111 11111111 11111111 11100000Set Host Bits Of Subnet Address To 1. This is the broadcast.

11000111 01011010 11001000 01111111

Broadcast, Decimal 199 90 200 127 The broadcast address is 199.90.200.127. What is the broadcast address for the subnet where the address 189.90.94.25 /28 can be found? IP Address 10111101 01011010 01011110 00011001Subnet Mask 11111111 11111111 11111111 11110000Boolean AND Result 10111101 01011010 01011110 00010000Set Host Bits Of Subnet Address To 1. This is the broadcast.

10111101 01011010 01011110 00011111

Broadcast, Decimal 189 90 94 31 The broadcast address for this subnet is 189.90.94.31. What is the broadcast address for the subnet where the address 10.4.200.67 /26 can be found? IP Address 00001010 00000100 11001000 01000011Subnet Mask 11111111 11111111 11111111 11000000Boolean AND Result 00001010 00000100 11001000 01000000Set Host Bits Of Subnet Address To 1. This is the broadcast.

00001010 00000100 11001000 01111111

Broadcast In Decimal 10 4 200 127 The broadcast address for this subnet is 10.4.200.127.


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What is the broadcast address for the subnet where the address 251.12.79.14 /30 can be found? IP Address 11111011 00001100 01001111 00001110Subnet Mask 11111111 11111111 11111111 11111100Boolean AND Result 11111011 00001100 01001111 00001100Set Host Bits Of Subnet Address To 1. This is the broadcast.

11111011 00001100 01001111 00001111

Broadcast In Decimal 215 12 79 15 The broadcast address for this subnet is 215.12.79.15. What is the range of valid host addresses in the subnet 189.57.34.64 /26? Identify the host bits. Determine the subnet (all-zeroes) and broadcast (all-ones) addresses for the subnet; all hosts between those two are valid. Subnet 10111101 00111001 00100010 01000000Subnet Mask 11111111 11111111 11111111 11000000Subnet Address 10111101 00111001 00100010 01000000Broadcast Address 10111101 00111001 00100010 01111111 Subnet Address: 189.57.34.64. Broadcast address: 189.57.34.127. Valid range of host addresses: 189.57.34.65 – 189.57.34.126.


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True or False: By default, a Class B address has 16 network bits and 16 host bits. Answer: True. True or False: When configuring subnetting, the subnet bits are borrowed from the network bits. Answer: False. Subnet bits are borrowed from the host bits. The number of network bits stays the same. True or False: When configuring subnetting, the "all-ones" subnet an "all-zeroes" subnets are considered unusable. Answer: True. Technically, they can be used, but Cisco discourages their use. For exam purposes, consider these networks unusable. True or False: When configuring subnetting, the "all-ones" host address is considered usable as a host address, but the "all-zeroes" host address is not. Answer: False. The "all-ones" host address is the broadcast address, while the "all-zeroes" host address is the subnet address itself. True or False: Someone mentions the subnet mask "slash nine". In dotted decimal, this is a mask of 255.128.0.0. Answer: True. "slash nine" refers to a mask of /9, which means the first nine bits of the mask are ones, and the rest are zeroes. In binary, that's 11111111 10000000 00000000 00000000; in dotted decimal, that's 255.128.0.0. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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What is the valid range of host addresses in the subnet 190.45.224.4 /30 subnet? Identify the host bits. Determine the subnet (all-zeroes) and broadcast (all-ones) addresses for the subnet; all hosts between those two are valid. Subnet 10111110 00101101 11011110 00000100Subnet Mask 11111111 11111111 11111111 11111100Subnet Address 10111110 00101101 11011110 00000100Broadcast Address 10111110 00101101 11011110 00000111 Subnet address: 190.45.224.4. Broadcast address: 190.45.224.7. Valid range of host addresses: 190.45.224.5 – 6 What is the valid range of host addresses in the subnet 244.18.25.0 /25? Identify the host bits. Determine the subnet (all-zeroes) and broadcast (all-ones) addresses for the subnet; all hosts between those two are valid. Subnet 11110100 00010010 00001001 00000000Subnet Mask 11111111 11111111 11111111 10000000Subnet Address 11110100 00010010 00001001 00000000Broadcast Address 11110100 00010010 00001001 01111111 Subnet address: 244.18.25.0. Broadcast address: 244.18.255.127. Valid range of host addresses: 244.18.25.1 – 126.


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What is the valid range of host addresses in the 109.87.35.24 /29 subnet? Identify the host bits. Determine the subnet (all-zeroes) and broadcast (all-ones) addresses for the subnet; all hosts between those two are valid. Subnet 01101101 01010111 00100011 00011000Subnet Mask 11111111 11111111 11111111 11111000Subnet Address 01101101 01010111 00100011 00111000Broadcast Address 01101101 01010111 00100011 00111111 Subnet address: 109.87.35.24. Broadcast address: 109.87.35.31. Valid range of host addresses: 109.87.35.25 – 30. What is the valid range of host addresses in the 41.29.87.0 /28 subnet? Identify the host bits. Determine the subnet (all-zeroes) and broadcast (all-ones) addresses for the subnet; all hosts between those two are valid. Subnet 00101001 00011101 01010111 00000000Subnet Mask 11111111 11111111 11111111 10000000Subnet Address 00101001 00011101 01010111 00000000Broadcast Address 00101001 00011101 01010111 00001111 Subnet address: 41.29.87.0. Broadcast address: 41.29.87.15. Valid range of host addresses: 41.29.87.1 – 14


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You are working with network 130.10.0.0. Your network plan calls for a minimum of 150 subnets, but no more than 400. What is the appropriate subnet mask? This is a Class B network. The default mask is 255.255.0.0. You will need 8 subnet bits (2 to the 8th power – 2 = 252) to meet both requirements. The subnet mask is 255.255.255.0. Default Class B Mask 11111111 11111111 00000000 00000000Borrow Eight Host Bits For Subnet Mask

11111111

Final Subnet Mask 11111111 11111111 11111111 00000000 You are working with network 10.0.0.0. Your network plan calls for a minimum of 30 subnets, but you must not have more than 35. What is the appropriate subnet mask? This is a Class A network. The default mask is 255.0.0.0. You will need 5 subnet bits (2 to the 5th power – 2 = 30) to meet both requirements. The final subnet mask is 255.248.0.0. Default Class A Mask 11111111 00000000 00000000 00000000Borrow Five Host Bits For Subnet Mask

11111

Final Subnet Mask 11111111 11111000 00000000 00000000 You are working with network 210.45.10.0. Your network plan calls for at least 10 subnets, but not more than 20. What is the appropriate subnet mask? This is a Class C network. The default mask is 255.255.255.0. You will need 4 subnet bits (2 to the 4th power – 2 = 14) to meet both requirements. The final subnet mask is 255.255.255.240. Default Class C Mask 11111111 11111111 11111111 00000000Borrow Eight Host Bits For Subnet Mask

1111

Final Subnet Mask 11111111 11111111 11111111 11110000 Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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You are working with network 199.20.14.0. Your network plan calls for at least 60 subnets. Can this be done? If so, what is the appropriate subnet mask? This is a Class C network. The default mask is 255.255.255.0. You will need 6 subnet bits (2 to the 6th power – 2 = 62) to meet both requirements. This is a valid configuration. The final subnet mask is 255.255.255.252. Default Class B Mask 11111111 11111111 11111111 00000000Borrow Eight Host Bits For Subnet Mask

111111

Final Subnet Mask 11111111 11111111 11111111 11111100 You are working with network 215.18.20.0. Your network plan calls for at least 150 subnets. Can this be done? If so, what is the appropriate subnet mask? This is a Class C network. The default mask is 255.255.255.0. For at least 150 subnets, seven subnet bits would be needed. This would leave only one host bit, an invalid configuration. Never attempt to use a subnet mask of /31 or 255.255.255.254. This is an invalid mask. You are working with network 17.0.0.0. You want to allow for 1000 hosts, but no more than 1100. What is the appropriate subnet mask? This is a Class A network. The default mask is 255.0.0.0. To allow for 1000 hosts but no more than 1100, ten host bits will be needed (2 to the 10th power – 2 = 1022). The final subnet mask is 255.255.252.0.


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Default Class A Mask 11111111 00000000 00000000 00000000Only Ten Host Bits Can Be Used

00 00000000

Final Subnet Mask 11111111 11111111 11111100 00000000 You are working with network 150.45.0.0. You want to allow for 60 hosts, but not more than 100. What is the appropriate subnet mask? This is a Class B network. The default mask is 255.255.0.0. To allow for 60 hosts but no more than 100, six host bits will be needed (2 to the 6th power – 2 = 62). The final subnet mask is 255.255.255.192. Default Class B Mask 11111111 11111111 00000000 00000000Only Six Host Bits Can Be Used

000000

Final Subnet Mask 11111111 11111111 11111111 11000000 You are working with network 217.28.100.0. You want to allow for a minimum of 25 hosts and a maximum of 30. What is the appropriate subnet mask? This is a Class C network. The default mask is 255.255.255.0. To allow for 25 hosts but no more than 30, 5 host bits will be needed (2 to the 5th power – 2 = 30). The final subnet mask is 255.255.255.248. Default Class A Mask 11111111 00000000 00000000 00000000Only Ten Host Bits Are Needed

00 00000000

Final Subnet Mask 11111111 11111111 11111100 00000000 Is it possible to configure a valid subnet mask that allows only a single valid IP address? No. Such a mask would appear as 255.255.255.254, or /31. Never attempt to use such a mask. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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You are working with network 182.10.0.0. You want to allow for at least 250 subnets, but no subnet must allow more than 130 hosts. What is the appropriate subnet mask? There are two values to watch here. This Class B network has a default mask of 255.255.0.0, leaving 16 bits to split between the subnet and host bits. Eight subnet bits would yield 254 usable subnets (2 to the 8th power – 2 = 254), but it would also leave eight host bits, yielding 254 hosts, violating the requirement. Nine subnet bits would give you 510 subnets and only 126 hosts. This results in a subnet mask of 255.255.255.128. Watch this kind of question very carefully. You are working with network 220.10.15.0. You want to allow for at least 29 hosts per subnet, but you must never have more than three subnets. What is the appropriate mask? Watch both values in these questions. This Class C network has a default mask of 255.255.255.0, leaving eight bits to split between the subnet and host bits. Five host bits would result in 30 valid hosts (2 to the 5th power – 2 = 30), but would leave three subnet bits, which allows six subnets, violating the requirement. Using two subnet bits meets both requirements, and results in a mask of 255.255.255.192. You are working with network 17.0.0.0. You want to allow for at least 1000 subnets. No subnet should ever have more than 1025 hosts. What is the appropriate mask? This Class A network has a default mask of 255.0.0.0, leaving 24 bits to split between the subnet and host bits. 10 subnet bits would result in 1022 valid subnets (2 to the 10th power – 2 = 1022), but would leave too many bits for the hosts. Using that equation, 10 host bits would result in 1022 hosts. Using the middle 14 bits for the subnets meets the requirement. This results in a subnet mask of 255.255.252.0.


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Is a subnet mask of 255.255.254.0 valid? Yes. This is simply a /23 mask, or “slash twenty-three”. There is no problem with a “254” in any octet except the final one. 255.255.254.0 is fine; 255.255.255.254 is not. You are working with network 150.5.0.0. Your network manager asks you to come up with a subnetting scheme that will allow for at least 750 subnets, and at least 57 hosts per segment. What subnet mask will you use? This Class B network has a default mask of 255.255.0.0, leaving 16 bits to split between the subnet and host bits. For 750 subnets, 10 subnet bits are needed (2 to the 10th power – 2 = 1022). This leaves 6 host bits, resulting in 62 usable host addresses. This meets the requirement. The final mask is 255.255.255.192. You are working with network 220.90.253.0. Your network manager has asked you to come up with a subnetting scheme that allows for no more than 14 subnets, and no more than 14 users per subnet. What subnet mask will you use? This Class C network has a default mask of 255.255.255.0, leaving 8 bits to split between the subnet and host bits. Splitting these bits evenly results in 14 valid subnets and 14 valid host addresses. The subnet mask is 255.255.255.240.


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Section Six: Initial Router Configuration Questions Where does a Cisco router hold its IOS images? In Flash memory. Are the contents of Flash memory kept on reload? Yes. Are the routing tables kept in Read-only memory (ROM), Random-access memory (RAM), or Flash? Routing tables, along with the running configuration file, are kept in RAM. RAM contents are lost on reload. Where does a Cisco router keep the startup configuration file? The startup configuration file is kept in NVRAM, or non-volatile RAM. NVRAM contents are retained on reboot. What is the very first step in the router boot process? The Cisco router will run a POST (power-on self-test). The POST is a series of diagnostic tests designed to verify the basic operations of the CPU and router memory. From what three locations can a Cisco router load the IOS? The Internetwork Operating System can be loaded from Flash, a TFTP server, or ROM. What is the default location that a Cisco router attempts to first load the IOS upon startup? The router will attempt to load the IOS from Flash memory.


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If there is no valid startup configuration, what mode does the router enter? The router will enter setup mode, which is a series of yes / no questions requiring user input. What mode is this router in? Router> This router is in user exec mode. From this prompt, what will the user have to enter to access privileged exec mode? Router> Type in the word enable and press <ENTER>. What mode is this router in? Router# This router is in privileged exec mode. From this mode, what would the user need to enter to be in user exec mode? Router# This user is in privileged exec mode. To enter user exec mode, type logout and press <ENTER>. What mode is this router in? Router(config)# This user is in global configuration mode. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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You want to name this router ROUTER1. What should you enter at this prompt to do so? Router(config)# Enter the command hostname ROUTER1, and hit <ENTER>. You are in global configuration mode and have entered several global commands. What key combination will bring you back to privileged exec mode and save your changes to the running configuration? <CTRL-Z> puts you back in privileged exec and saves your changes to the running configuration. It appears this way on the screen: Router(config)#hostname R3 R3(config)#^Z R3# What is true of any command set in global configuration mode? Any command entered in global configuration mode affects the entire router and only needs to be entered once. You are at the following prompt and want to configure interface Serial0. What should you enter? R3(config)# Interface serial0 What mode is this router in? R3(config-if)# This router is in interface configuration mode. What single character accesses IOS Help? A question mark. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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You want to configure a loopback interface with the IP address 10.7.7.7 255.255.255.0. What is the correct mode and syntax? Enter interface configuration mode and configure the address: R3(config)#interface loopback0 R3(config-if)#ip address 10.7.7.7 255.255.255.0 You want to protect privileged exec mode with a password. What two commands can you use to do so? You can use the global commands enable secret or enable password. Your router has an enable password and an enable secret password set. Which, if either, will the router prompt the user for when they attempt to enter privileged exec mode? If both passwords are set, the enable secret password is used. The enable password is used primarily for backward compatibility with older routers. You want to protect the console with a password. What command should be entered at this prompt to do so? R3(config)# You need to enter line configuration mode to do this. Enter line console 0 first, then enter the appropriate commands. Example: R3(config)#line console 0 R3(config-line)#login R3(config-line)#password CISCO What global configuration command will encrypt all passwords in the running configuration? Service password-encryption Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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What command globally disables Cisco Discovery Protocol? No cdp run What command globally enables Cisco Discovery Protocol? Cdp run What command disables Cisco Discovery Protocol on the interface level? No cdp enable What command enables Cisco Discovery Protocol on the interface level? Cdp enable What command produced this console output? R2# Global CDP information: Sending CDP packets every 60 seconds Sending a holdtime value of 180 seconds Show cdp


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Section Seven: Static and DV Routing Questions In a routing table, what does the letter “C” indicate? A directly connected route. What is a loopback address? A loopback address is a logical interface with an IP address. It can only go down if the router itself goes down. What command is used to configure a static route? Ip route What command displays the routing table? Show ip route In the command “ip route 2.2.2.2 255.255.255.255 172.12.123.1”, what does the “172.12.123.1” indicate? The IP address of the next hop to the destination. What command creates a default static route with the next-hop address of 10.1.1.1? Ip route 0.0.0.0 0.0.0.0 10.1.1.1 What is the primary metric used by a distance vector protocol to determine the best path to a destination? Hop count. What does split horizon do? Split horizon prevents a route from being advertised out the same interface upon which the advertisement for that same network was originally received.


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A router realizes a directly connected route is no longer available. That router continues to advertise the route, but with an unreachable metric. What distance vector behavior is in use? Route poisoning. What hop count is considered unreachable by a distance vector protocol? 16 What command shows RIP routes contained in a routing advertisement? Debug ip rip What is the default setting for RIP version 2 auto-summarization? What command changes this? Auto-summarization is on by default in RIPv2. The command “no auto-summary” turns it off. What command enables RIP on a router? Router rip What term describes the situation where all routers in a network recognize that a change in the network has occurred, and have all adjusted their routing table accordingly? Convergence. When a route is said to be “flapping”, what’s happening to it? A flapping route is one that is available, then unavailable for a few seconds, then available again, then unavailable again.


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What is a triggered update? A triggered update is an update that is sent immediately due to a change in the network topology, rather than waiting for the regularly scheduled update. When configuring RIP, what command indicates what interfaces should participate in RIP routing? Network What command will show all protocols running on a router? Show ip protocols What are RIP’s default timers? Updates are sent every 30 seconds; the invalid and holddown timers are both 180 seconds by default; the flush timer is set to 240 seconds. By default, what versions of RIP does a Cisco router send and receive? Cisco routers send RIP version 1, and receive both versions 1 and 2. What is the administrative distance of RIP? 120. Is RIP version 1 classful or classless? RIP Version 1 is classful. It does not recognize Variable-Length Subnet Masking.


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In router config mode, what command will prevent RIP from sending or receiving version 2 updates? Version 1 What command will display RIP’s authentication scheme? Show ip protocols In the following line, what does the “1” in the brackets indicate? R 2.0.0.0/8 [120/1] via 172.12.21.2, 00:00:24, Dialer1 The “1” in the brackets is the RIP metric, the hop count. By default, how many paths will RIP perform equal-cost load balancing? Four. What command is used to change the default number of paths used in RIP’s equal-cost load balancing? Under the RIP routing process, configure maximum-paths. What term is used to measure a protocol’s believability? Administrative Distance. Which will the router prefer, the lowest Administrative Distance or the highest? The lowest Administrative Distance is the most believable and is the most preferred. What is RIP’s sole metric? Hop count. Is RIP version 2 considered classful or classless? Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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RIP version 2 is classless; it supports Variable-Length Subnet Masking. You want to configure authentication on your RIP domain. Does it matter which version you use? Yes. RIP version 1 doesn’t support authentication, but RIP version 2 does. What authentication types are available for RIP? Clear-text and MD5. You have created a key chain with the name CISCO, and wish to use clear-text authentication. What two interface-level commands will do this? Ip rip authentication mode text Ip rip authentication key-chain CISCO Can RIP authentication be run over a single link in a RIP network, or must it be run on all links in the network? RIP authentication can run over a single link, as long as it’s configured on both ends of the link. You have created a key chain with the name PASSEDCCNA, and wish to use MD5 authentication. What two interface-level commands will do this? Ip rip authentication mode md5 Ip rip authentication key-chain PASSEDCCNA What command is commonly used to quickly send routing updates, rather than waiting for the next scheduled update? Clear ip route *


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To what address are RIP version 1 updates sent? RIP version 1 updates are broadcast to 255.255.255.255. To what address are RIP version 2 updates sent? RIP version 2 updates are multicast to 224.0.0.9. What command will display only the RIP routing table? Show ip route rip What command turns off all currently running debugs? Undebug all According to this debug, what version of RIP is running? RIP: sending update to 255.255.255.255 via Serial0 (172.12.123.1) The update is sent to the broadcast address 255.255.255.255, so it’s RIP version 1. According to this “show dialer” output, what brought this link up? Dial reason: ip (s=172.12.21.2, d=224.0.0.9) The destination is 224.0.0.9, so RIP version 2 is in use. What command allows RIP and IGRP to receive updates, but not send them on a particular interface? Passive-interface


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In the command “router igrp 1”, what meaning does the “1” have? The number following “router igrp” represents the Autonomous System number. Do IGRP routes in different Autonomous Systems exchange routes by default? No. Redistribution has to be configured. What is the default number of paths IGRP will use for equal-cost load balancing? Four. What command changes the default number of paths IGRP will use for equal-cost load balancing? The IGRP router process command maximum-paths. What is the maximum number of paths IGRP will use for equal-cost load balancing? Six. What command will prevent IGRP from performing equal-cost load balancing? The command “maximum-paths 1” will do this. In this line from an IP routing table, what does the “8976” represent? I 2.0.0.0/8 [100/8976] via 172.12.123.2, 00:00:01, Serial0 The “8976” is the IGRP metric. What is the Administrative Distance of IGRP? 100. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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What other factors than hop count can IGRP consider in determining a path’s metric? Bandwidth, delay, load, and reliability. By default, what other factors besides hop count does IGRP consider when determining a path’s metric? Bandwidth and delay. What assumption does IGRP make concerning a Serial interface? IGRP assumes a Serial interface is a T1 line, which has a speed of 1544 kbps. What command changes the value IGRP uses for a Serial interface’s bandwidth? The interface-level command “bandwidth”. Note that this does not actually change the bandwidth of the interface. It only changes the value IGRP will use in configuring the route’s metric. What command is used to allow IGRP to use unequal-cost load balancing? Variance Describe IGRP’s “feasibility condidtion”. For a route to be a feasible successor, the next-hop router must have a metric to the destination that is lower than the local router’s metric for that destination. In IGRP, what debug command will show the current metric for all routes? Debug ip igrp transactions


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By default, does IGRP unequal-cost load balancing send an equal amount of data over all paths? No. IGRP will have the better routes carry proportionally more traffic. What command configures IGRP to have all load-balancing paths carry approximately the same amount of traffic, regardless of metric? Traffic-share balanced What command is used to send all data over only the lowest-cost route when unequal-cost load balancing is in use? Traffic-share minimum What command will show IGRP routes entering and leaving an interface? Debug ip igrp events To what address does IGRP send routing updates? IGRP broadcasts routing updates to 255.255.255.255. Is IGRP considered classful or classless? IGRP is considered classful. It does not understand Variable-Length Subnet Masking. You want to configure a static route to network 100.10.1.0 /24. Traffic using the static route will exit your router’s Ethernet1 interface. What command will do this? Ip route 100.10.1.0 255.255.255.0 ethernet1


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You want to configure a default static route. Traffic using this default static route will have a next-hop address of 172.16.4.4. What command will do this?


Ip route 0.0.0.0 0.0.0.0 172.16.4.4 In the following router configuration, what effect does the passive-interface line have? R1(config)#router igrp 1 R1(config-router)#network 172.12.0.0 R1(config-router)#network 1.0.0.0 R1(config-router)#passive-interface dialer1 The passive-interface command means that Dialer1 will still receive IGRP updates, but will not send them. R1 is running IGRP. Exactly what effect does the following configuration have on the router and the routing process? R1#conf t R1(config)#interface serial1/0 R1(config-if)#bandwidth 512 By default, IGRP assumes all Serial interfaces are running at T1 speed, and uses 1544 kbps as the bandwidth metric when calculating routes. This command changes IGRP’s assumption of the interface’s speed; it does NOT actually change the transmission speed. Why are there two routes to a single destination in this routing table? R1#show ip route igrp I 2.0.0.0/8 [100/8976] via 172.12.123.2, 00:00:17, Serial0/0 I 3.0.0.0/8 [100/8976] via 172.12.123.3, 00:00:24, Serial0/0 I 172.23.0.0/16 [100/8576] via 172.12.123.3, 00:00:24, Serial0/0 [100/8576] via 172.12.123.2, 00:00:17, Serial0/0 Because IGRP has equal-cost load balancing over up to four paths enabled by default. These paths have the same metric, 8576, so equal-cost load balancing is in effect. \


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You have just cleared the routing table and you see this console output. What IGRP command is running? R1#clear ip route * 05:40:07: IGRP: received update from 172.12.13.3 on Serial1/0 05:40:07: subnet 172.12.123.0, metric 23531 (neighbor 8476) 05:40:07: network 1.0.0.0, metric 24031 (neighbor 8976) 05:40:07: network 2.0.0.0, metric 22131 (neighbor 1600) 05:40:07: network 3.0.0.0, metric 22031 (neighbor 501) 05:40:07: network 172.23.0.0, metric 21631 (neighbor 1100) debug ip igrp transactions is running. This is an excellent command to determine what value the variance command will need to be in order to enable unequal-cost load balancing. Your IGRP routing table indicates the best metric for a certain destination is 8500. You then see that the second-best metric for that destination is 22400. What is the lowest value you can use with the variance command and still enable unequal-cost load balancing? Variance 3 will do the job. 8500 * 3 = 25500; as long as the other path is a feasible successor, variance 3 will enable unequal-cost load balancing. What IGRP command is in effect, judging from this routing table entry? R1#show ip route igrp I 2.0.0.0/8 [100/22131] via 172.12.13.3, 00:00:04, Serial1/0 [100/9076] via 172.12.123.3, 00:00:04, Serial0/0 [100/8976] via 172.12.123.2, 00:00:04, Serial0/0 The metrics indicate that variance 3 is in effect. The first two paths would not be in the table otherwise, since the metrics are not equal. Is this configuration correct, or are wildcard masks needed next to the network statements? R1(config)#router rip R1(config-router)#version 1 R1(config-router)#passive-interface dialer1 R1(config-router)#network 172.12.0.0 R1(config-router)#network 1.0.0.0


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This configuration is correct. Wildcard masks are not configured with RIP versions 1 or 2. Why are there three routes to this network in the RIP routing table? R1#show ip route rip R 172.23.0.0/16 [120/1] via 172.12.123.2, 00:00:09, Serial0 [120/1] via 172.12.13.3, 00:00:04, Serial1 [120/1] via 172.12.123.3, 00:00:04, Serial0 RIP has equal-cost load-balancing enabled by default, up to four paths. What is the effect of the following router configuration? R1#conf t R1(config)#router rip R1(config-router)#maximum-paths 6 This configuration allows RIP to use up to six paths for load sharing. The default is four. Exactly what protocol discovered this route? R1# 2.0.0.0/27 is subnetted, 1 subnets R 2.2.2.0 [120/1] via 172.12.123.2, 00:00:15, Serial0 RIP version 2 discovered this route. The “R” indicates a RIP route, and the /27 mask indicates that variable-length subnet masks are in use. RIP version 1 does not recognize VLSMs. What command resulted in this console output? R1# 22:51:38: RIP: sending general request on Loopback0 to 224.0.0.9 22:51:38: RIP: sending general request on Serial0 to 224.0.0.9 22:51:38: RIP: sending general request on Serial1 to 224.0.0.9 22:51:38: RIP: received v2 update from 172.12.13.3 on Serial1 22:51:38: 172.12.13.0/24 -> 0.0.0.0 in 1 hops 22:51:38: 172.12.123.0/24 -> 0.0.0.0 in 1 hops 22:51:38: 2.2.2.0/27 -> 0.0.0.0 in 2 hops 22:51:38: 3.3.3.0/27 -> 0.0.0.0 in 1 hops 22:51:38: 172.23.23.0/27 -> 0.0.0.0 in 1 hops debug ip rip displays this helpful information. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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In this routing table line, what does the “1” in the brackets mean? S 2.2.2.2 [1/0] via 172.12.123.1 The “1” is the Administrative Distance of the route. Static routes have an AD of 1 by default. What command resulted in this console output? R3# Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds: !!!!! ping 2.2.2.2 What do the symbols at the end of this console output mean? R3#ping 2.2.2.2 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds: !!!!! Exclamation points for a ping response indicate that the ping was successful and there is connectivity. What do the symbols at the end of this console output mean? R3#ping 2.2.2.2 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds: ….. Periods indicate that the ping packets have timed out and IP connectivity is not present. You have configured a default static route. The next-hop IP address is 172.12.123.8. What is the correct command to remove this route? No ip route 0.0.0.0 0.0.0.0 172.12.123.8 82 questions. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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You want to send a ping to a neighboring router via your router’s E0 interface. You want to use your loopback interface as the source of the ping. How can you do this? Send an extended ping by simply entering the command “ping”, then hit < ENTER >. You will then be presented with a series of questions. When asked if you want to enter extended commands, say yes. One of the questions will be what interface should serve as the source of the ping. What kind of route is indicated by the letter “S”? A directly connected route. What is the administrative distance of a directly connected route. Zero. What’s wrong with the following static route statement? ip route 0.0.0.0 255.255.255.255 ethernet0 The network mask should be “0.0.0.0”, not “255.255.255.255”. True or False: Configuring the bandwidth interface-level command in IGRP will affect the rate at which data is transmitted over that interface. False. The bandwidth command in IGRP only affects the computation of the IGRP metric. This command does not actually affect the transmission rate of data. True or False: You have unequal-cost load sharing configured with IGRP. You want the slow links to carry approximately the same amount of data as the fast links. The command “traffic-share balanced” will allow this. True. Traffic-share balanced allows slow links to carry almost the same amount of data as fast links.


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True or False: The Administrative Distance of an IGRP route is 100. True. True or False: The Administrative Distance of a RIP route is 110. False. The AD of a RIP route is 120. True or False: RIP version 2 uses the address 224.0.0.9 to send routing updates. Answer: True. RIP version 2 multicasts to 224.0.0.9, while RIP version 1 broadcasts to 255.255.255.255.


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Section Eight: OSPF and Link-State Questions In the command “router ospf 1”, what does the “1” refer to? The OSPF router process number. You have two OSPF router processes, OSPF 1 and OSPF 2. Will these router processes automatically exchange routes? No. OSPF router processes are totally separate. Redistribution would have to be configured manually. What command prevents an OSPF router from possibly being elected Designated Router or Backup Designated Router? Place the command ip ospf priority 0 on the interfaces that should not participate in the DR or BDR election. What is the default priority of an OSPF interface? One What interface-level command will make an interface send OSPF Hello packets every 5 seconds? Ip ospf hello-interval 5 What command will help you diagnose an OSPF neighbor adjacency problem? Debug ip ospf adjacency You want to create a virtual link from R1 to R3. R3’s OSPF Router ID is 3.3.3.3; the link will cross Area 17. What command should be configured on R1? Under the OSPF router process, configure area 17 virtual-link 3.3.3.3


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By what two names is the algorithm run by OSPF known? The SPF algorithm (Shortest Path First), or the Dijkstra algorithm. You have three routers all in OSPF 14. Will these routers exchange OSPF routes? No. OSPF routers do not exchange routes, as RIP and IGRP do. They exchange Link State Updates, which contain Link State Advertisements. The Dijkstra algorithm is then run to calculate the best routes. After the initial route calculation, when do routers send LSAs in OSPF? LSAs are sent upon a change in the network topology. They do not go out at a timed interval. To what address do OSPF routers flood changes in the network topology? 224.0.0.5. On an Ethernet segment, by default, how often will OSPF send a Hello packet? OSPF sends Hello packets every 10 seconds on an Ethernet segment. On a Serial interface, by default, how often will OSPF send a Hello packet? OSPF sends Hello packets every 30 seconds on a non-broadcast link, such as a Serial link. By default, what is the OSPF dead time on an Ethernet link?


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By default, OSPF dead time is four times the Hello time; on an Ethernet link, that is 4 x 10 seconds, or 40 seconds. By default, what is the OSPF dead time on a Serial link? By default, OSPF dead time is four times the Hello time; on a Serial link, that is 4 x 30 seconds, or 120 seconds. What is OSPF’s main method of loop prevention? The Dijkstra algorithm. This algorithm recalculates network changes so quickly that loops have no time to form. OSPF does not use Split Horizon or Poison Reverse – those are Distance Vector methodologies. In a hub-and-spoke configuration, what is true of the Designated Router and Backup Designated Router? The hub router must be the DR. There will be no BDR. When OSPF routers in a hub-and-spoke configuration flood changes to 224.0.0.5, to what particular OSPF device are they flooding the changes to? The Designated Router. In a hub-and-spoke configuration, what additional configuration is needed on the hub that is not needed on the spokes? The neighbor command is needed on the hub. This command will give the hub the IP addresses of the spokes. Your router has the following interfaces. Only the Serial interfaces are running OSPF. What is the Router ID of this router? Serial0: 172.15.1.1 Serial1: 172.178.34.12 Ethernet0:200.1.1.1 The RID is 200.1.1.1. OSPF prefers a loopback address as the RID, but there isn’t one. OSPF will then use the highest IP address of any


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interface on the router. The interface does NOT have to be OSPF-enabled. Your router has the following interfaces. All are running OSPF. What is the Router ID of this router? Serial0: 215.1.1.1 Serial1: 212.1.1.1 Ethernet0: 245.54.45.45 Loopback1: 10.1.1.1 Loopback2: 5.2.2.2 The RID is 10.1.1.1. OSPF prefers a loopback address as the RID and will always use the highest IP address of a loopback before it will use any address on another interface type. Without changing any IP addresses on a router, how can you set the OSPF Router ID to 45.1.1.1 ? Use the OSPF router process command router-id 45.1.1.1. What term is used to describe an OSPF router with all its interfaces in the same area? An Internal Router. What term is used to describe an OSPF router with at least one interface in Area 0, but does not necessarily connect other areas to Area 0? Backbone Router What term is used to describe an OSPF router with at least one interface in Area 0, and connects other areas to Area 0? Area Border Router What term is used to describe as OSPF router that takes routes from other protocols and places them into the OSPF domain?


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Autonomous System Border Router Looking at this console readout, what is absolutely true of this router? R1#show ip ospf Routing Process "ospf 1" with ID 1.1.1.1 It is an area border router An Area Border Router has at least one interface in Area 0 and one in another area. The RID is 1.1.1.1, but that could be done with the router-id command, or it could be the IP address of a loopback interface. In a multi-area OSPF configuration, what is true of all non-Area 0 areas? All other areas must have a physical or logical connection to Area 0. If a router has no physical connection to Area 0, what should be done on that router? A virtual link should be configured to a router that does have an interface in Area 0. How does the presence of a stub area affect virtual link configuration? A virtual link cannot be configured through a stub area. You decide to create OSPF Area 5, and you want this area to receive no external routes. What command will perform this action? To block external routes from entering an area, configure the area as a stub area with the area 5 stub command under the OSPF process. How does an ABR allow a stub router to reach a destination whose route was learned via redistribution? Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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An ABR will send a stub router a default route, which the stub router can use to reach external destinations. What command will configure a router in Area 1 as a total stub area? Under the OSPF process, configure area 1 stub no-summary. You have just changed the OSPF Router ID with the router-id command. What has to be done to make this change take effect? You can either reboot the router, or clear the OSPF process with clear ip ospf process. Note that clearing the OSPF process will cause all existing adjacencies on this router to be lost. You are running OSPF over an ISND dial-on-demand link. You notice packets for destination 224.0.0.5 are keeping the line up. What OSPF command can be used to prevent this behavior? Configure ip ospf demand-circuit under the BRI interface on one side of the link. (Putting it on both sides doesn’t hurt anything, but it’s only needed on one side.) You want to send OSPF Hellos on your Ethernet0 interface every 5 seconds. What command will perform this action? On the Ethernet interface, configure ip ospf hello-interval 5. True or False: All OSPF hub-and-spoke networks must contain a Designated Router. Answer: True. Whether configured by design or left to defaults, a DR will always be elected. True or False: All OSPF networks must contain a Backup Designated Router.


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Answer: False. In some cases, such as a hub-and-spoke configuration, it's desirable to NOT have a BDR. True or False: To prevent a router from becoming a BDR, configure "no ip ospf bdr" on the appropriate interface. Answer: False. Place the interface-level command "ip ospf priority 0" on the proper interface. True or False: A virtual link cannot be configured through a stub area. Answer: True. Virtual links cannot traverse stub areas of any kind. True or False: The algorithm that OSPF performs to determine optimal paths is DUAL. Answer: False. OSPF uses the Dijkstra algorithm. EIGRP performs DUAL. True or False: In OSPF, if the Hello packets are sent every 12 seconds, the OSPF dead-time by default is 48 seconds. Answer: True. By default, OSPF's dead-time is four times the Hello time. True or False: In a hub-and-spoke OSPF configuration, the "neighbor" command will only be used on the DR. Answer: True. The "neighbor" command always goes on the hub router only. True or False: The OSPF RouterID (RID) is the numerically highest IP address on the router. Answer: False. The numerically highest IP address on the LOOPBACK address is the OSPF RID. You can have numerically higher addresses on other interfaces, but the loopback takes precedence.


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True or False: OSPF must always have an Area 0. Answer: False. IF there is only one area, that area can have any number. If there is more than one area, one of them has to be Area 0. The command "no ip ospf demand-circuit" will prevent an ISDN interface from coming up due to OSPF packets. Answer: False. The command is "ip ospf demand-circuit".


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Section Nine: EIGRP Questions You want to view your EIGRP neighbors, adjacencies, and the interface the adjacencies are formed on. What single command displays all this information? Show ip eigrp neighbor You’ve configured an EIGRP adjacency, but for some reason it’s not forming. What command should you run to see what the issue is? Debug ip eigrp neighbor What command is used to enable EIGRP unequal-cost load sharing? Variance What makes EIGRP a hybrid protocol? EIGRP has both link-state and distance-vector protocol characteristics. What distance-vector characteristics does EIGRP have? EIGRP initially exchanges a full routing table, and also uses bandwidth and delay in calculating a metric, like IGRP. What link-state characteristics does EIGRP have? Hello packets are used to keep neighbor relationships alive, and updates are only sent when the network topology changes. What address does EIGRP send Hello packets to? 224.0.0.10. What term is used in EIGRP to identify routers belonging to the same logical group?


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Autonomous System Will routers in different EIGRP autonomous systems automatically exchange routes? No. Route redistribution would have to be manually configured. You have two routing domains, IGRP AS 200 and EIGRP AS 200. Will route redistribution occur automatically? Yes. If the AS number is the same, IGRP and EIGRP will exchange routes dynamically. You have two routing domains, IGRP AS 150 and EIGRP AS 1500. Will route redistribution occur automatically? No. The AS number is different. Once an EIGRP adjacency has formed, what packets keep it alive? Hello packets perform this function. For an EIGRP adjacency to form, what two values must match? The AS number and the metric weights. What three tables does EIGRP keep? The route table, the topology table, and the neighbor table. What does EIGRP keep in the route table? The best route(s) to a destination. If load-sharing is in effect, each path participating in load sharing will appear in the route table. What does EIGRP keep in the topology table? The feasible successors. What term does EIGRP use for the best route to a destination?


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Successor What term does EIGRP use for routes to a destination that could be used in case the primary route becomes unavailable? Feasible successor. What algorithm does EIGRP use to issue queries to neighbors, looking for a loop-free route to a destination? DUAL. A router receives an EIGRP DUAL query for a loop-free route to a destination. The router doesn’t have one. What happens now? The router that received the DUAL query will now send a DUAL query of its own. This process continues until a loop-free route is found. Under what circumstance does EIGRP automatically summarize a route? When routes are sent across a network boundary. Can the autosummarization behavior of EIGRP be turned off? If so, how? Yes. Use the no auto-summary command in the EIGRP AS process. Router eigrp 100 No auto-summary By default, how many paths will EIGRP utilize for equal-cost load balancing? Four.


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What is the maximum number of paths EIGRP will use for equal-cost load balancing? Six. What command will make EIGRP use five paths for equal-cost load balancing? Maximum-paths 5 What command will prevent EIGRP from performing any kind of load balancing? Maximum-paths 1 Is authentication available with EIGRP? If so, what are the options? Yes, MD5 and text. Is EIGRP considered classful or classless? EIGRP is classless. Can variable-length subnet masks be used with EIGRP? Yes. Which of the following commands is the correct way to have interfaces in network 172.12.123.0 /24 run EIGRP? R1(config-router)#network 172.12.123.0 0.0.0.255 R1(config-router)#network 172.12.123.0 255.255.255.0 The correct mask is 0.0.0.255. EIGRP uses wildcard masks, not subnet masks.


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You want to see only the routes for EIGRP AS 200. What is the correct command? Show ip route eigrp 200 In the routing table, what letter indicates an EIGRP route? “D” What is the administrative distance of an EIGRP route? 90. You want to configure unequal-cost load balancing in your EIGRP network. What command will show you the feasible successors and their metrics? Show ip eigrp topology You see the following in your topology table. What command will enable unequal-cost load balancing? P 2.2.2.0/24, 1 successors, FD is 2297856 via 172.12.123.2 (2297856/128256), Serial0/0 via 172.12.123.3 (2323456/409600), Serial0/0 variance 2. In the following EIGRP command, what effect does the “0.0.0.0” have? R2(config-router)#network 2.2.2.2 0.0.0.0 A wildcard mask of 0.0.0.0 will ensure that this particular address is the only one in that network that will run EIGRP.


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Does EIGRP run Split Horizon? If so, what are the defaults for physical, point-to-point, and point-to-multipoint interfaces? EIGRP runs Split Horizon on all interfaces by default. What interface-level command would disable Split Horizon for EIGRP AS 100 routes? No ip split-horizon eigrp 100 In the following EIGRP topology table, what does the “P” in the left-hand column mean? Is this good or bad? P 1.1.1.0/24, 1 successors, FD is 128256 The “P” means the route is Passive; that is, it’s not being calculated by DUAL. This is good in that the route is stable. In the following EIGRP topology table, what does the “A” in the left-hand column mean? Is this good or bad? A 2.2.2.0/24, 1 successors, FD is 2297856 The “A” indicates that the route is Active, meaning it’s being calculated by DUAL. It’s bad if the route stays this way, because while the route is Active, it cannot transport packets, since a loop may exist. 40 questions. What term best describes the highlighted routes? TbCw©

R1#show ip eigrp topology P 2.2.2.0/24, via 172.12.123.2 (2297856/128256), Serial0/0 via 172.12.123.3 (2323456/409600), Serial0/0 P 3.3.3.0/24, via 172.12.123.3 (2297856/128256), Serial0/0 via 172.12.123.2 (2323456/409600), Serial0/0

he highlighted routes are successors. An EIGRP successor is the est route to a destination. hris Bryant, CCIE #12933 ww.thebryantadvantage.com

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2004 The Bryant Advantage

What term best describes the highlighted routes?

R1#show ip eigrp topology P 2.2.2.0/24, 1 successors, FD is 2297856 via 172.12.123.2 (2297856/128256), Serial0/0 via 172.12.123.3 (2323456/409600), Serial0/0 P 3.3.3.0/24, 1 successors, FD is 2297856 via 172.12.123.3 (2297856/128256), Serial0/0 via 172.12.123.2 (2323456/409600), Serial0/0

The highlighted routes are EIGRP feasible successors, which are valid backup routes to the primary route, or the successor. True or False: The letter “D” in a routing table indicates an EIGRP route. True. What command produced this output?

R1# IP-EIGRP neighbors for process 120 H Address Interface Hold Uptime SRTT RTO Q Seq Type (sec) (ms) Cnt Num 1 172.12.117.1 Se0/0 12 00:03:26 1 5000 0 3 0 172.12.117.2 Se0/0 131 00:03:28 1 5000 0 3

Show ip eigrp neighbor What command should be configured to turn EIGRP’s default autosummarization feature off?

R1#conf t R1(config)#router eigrp 100 R1(config-router)# R1(config-router)#network 172.12.123.0 0.0.0.255

No auto-summary


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You want to enable your loopback0 interface for EIGRP AS 100. The IP address of the loopback is 1.1.1.1. What command will configure this interface for EIGRP, but absolutely no other addresses in the 1.0.0.0 network? Configure the router as follows: R1(config)#router eigrp 100 R1(config-router)#network 1.1.1.1 0.0.0.0 A wildcard mask of 0.0.0.0 means only this exact interface will be enabled for EIGRP. What command will disable Split Horizon on this interface for EIGRP AS 100? R1#conf t R1(config)#int serial0/0 R1(config-if)# No ip split-horizon eigrp 100 What term is used to describe the highlighted EIGRP metric? R1#show ip eigrp topology P 2.2.2.0/24, 1 successors, FD is 2297856 via 172.12.123.2 (2297856/128256), Serial0/0 via 172.12.123.3 (2323456/409600), Serial0/0 The first number is the Feasible Distance; the second number, the highlighted on in this question, is the Advertised Distance. Comparing EIGRP and IGRP, which of the following do they both support? VLSMs, load balancing, classful routing, and authentication. Of these four features, the only one supported by both IGRP and EIGRP is load balancing, both equal-cost (by default) and unequal-cost (using the variance command.)


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Is there a good reason to ever use the command maximum-paths 1 when configuring EIGRP or IGRP? Yes. Maximum-paths 1 will prevent any kind of load balancing. What feature of EIGRP may need to be disabled if EIGRP is configured on a point-to-multipoint interface? Split Horizon. This router may receive an EIGRP route from one of the routers it reaches via this point-to-multipoint interface, and it would then be unable to advertise it to the other routers it reaches via the same interface. True or False: EIGRP and IGRP perform unequal-cost load balancing in much the same way. Answer: True. Both use the "variance" command to allow unequal-cost load balancing. True or False: EIGRP sends Hello packets to 224.0.0.9. Answer: False. EIGRP sends Hellos to 224.0.0.10. True or False: EIGRP uses "areas" to identify routers belonging to the same logical group. Answer: False. EIGRP uses Autonomous Systems to group routers. OSPF uses areas. True or False: Routers running IGRP and EIGRP will automatically exchange routes as long as the IGRP and EIGRP AS numbers are different. Answer: False. For route redistribution to occur automatically between IGRP and EIGRP, the AS numbers must be the same. Chris Bryant, CCIE #12933 www.thebryantadvantage.com

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True or False: By default, EIGRP will use four paths for equal-cost load balancing, and can use up to eight. Answer: False. The default is four, but EIGRP can only use up to six paths for load balancing. True or False; Both IGRP and EIGRP are considered classless routing protocols. Answer: False. EIGRP is classless, but IGRP is classful. True or False: The letters "EI" indicate EIGRP routes in the routing table. Answer: False. The letter "D" indicates an EIGRP route. True or False: The administrative distance of an EIGRP route is 90. Answer: True. True or False: EIGRP's autosummarization feature attempts to summarize routes anytime an EIGRP routing update is sent. Answer: False. EIGRP's autosummarization takes place at network boundaries. You note in the EIGRP tables that a route has two successors. How can this happen? When equal-cost load balancing is in effect, as it is by default with EIGRP, all the equal-cost best routes are successors.


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Section Ten: Advanced TCP/IP Questions What command is used to apply an access-list to VTY lines? Access-class. This is used to limit Telnet access. What command applies an access-list to a router interface? Ip access-group How many access lists can a single interface have applied at one time? Two – one inbound and one outbound. Once a match is found in an access-list, does the access-list keep running, or does it stop? The ACL will stop immediately. Once a match is found, that ‘s it. With access-lists, what does the term “implicit deny” refer to? All Cisco access-lists have an implicit deny at the end. There is an unseen “deny all” at the end of all Cisco ACLs. Traffic must be explicitly permitted in order for that traffic to go through. What numeric ranges do standard access lists have? Standard ACLs have the ranges 1 – 99 and 1300 – 1399. What numeric ranges do extended access lists have? Extended ACLs have the ranges 100 – 199 and 2000 – 2699. Do access lists use wildcard masks or subnet masks? Access lists use wildcard masks, not subnet masks.


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In a wildcard mask, does a bit set to zero mean the bit has to match, or that it doesn’t matter? Zeroes in wildcard masks indicate that this bit needs to match. In a wildcard mask, does a bit set to one mean the bit has to match, or that it doesn’t matter? A bit set to one in the wildcard mask means this is an “I don’t care” bit – it doesn’t have to match. What factor does a standard access list consider for matches? A standard access list only considers the source IP address for matching. Does the order of lines in a standard access list matter? Yes. The list runs from top to bottom, and when a match is found, the ACL is no longer run. If this is the only line of an ACL, what happens to traffic that doesn’t match this line? access-list 5 permit 172.12.12.0 0.0.0.255 The traffic will be denied by the unseen “implicit deny”. You have just configure access-list 5. What command will apply this list to Ethernet0’s incoming traffic? Ip access-group 5 in When configuring an ACL, what single word can be used to represent a wildcard mask of 0.0.0.0? The word “host” represents a wildcard mask of 0.0.0.0. This means that only the single address listed before the wildcard mask will match this particular line.


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When configuring an ACL, what single word can be used to represent a wildcard mask of 255.255.255.255? The word “any” is the same as configuring a wildcard mask of 255.255.255.255. You want access-list 15 to permit all traffic. What one-line command will do so? Access-list 15 permit any You want to create an extended access-list named “STOPALL”. What command creates this list? Ip access-list extended STOPALL Don’t forget the “ip” at the very front of a named ACL. What term is used for the combining of multiple, contiguous network routes into a single comprehensive route? Route summarization. What is the main benefit of route summarization? Route summarization brings the size of the routing table down, keeping it more manageable and reducing the amount of time it takes to find a route. You are running RIP and want to summarize the following routes: 110.4.0.0, 110.5.0.0, 110.6.0.0, and 110.7.0.0. All have a 16-bit mask. What command will summarize these routes? Ip summary-address 110.4.0.0 255.252.0.0 will summarize these routes. This is an interface-level command. You have just performed route summarization in RIP. What command will accelerate the advertisement of the new summary route?


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Clearing the routing table will do this. Use clear ip route *. What is the administrative distance of a RIP summary route? 110 – the same as a regular RIP route. You want to send a summary route of 172.16.8.0 /22 over an EIGRP interface. The AS number is 250. What command will do so? The interface-level command ip summary-address eigrp 250 172.16.8.0 255.255.252.0 At what point in the network is CIDR generally performed? The Internet Service Provider runs CIDR. Describe the purpose of CIDR. CIDR, Classless InterDomain Routing, is used by ISPs to perform route summarization and address conservation. What are the RFC 1918 private address ranges? 10.0.0.0 /8 172.16.0.0 /12 192.168.0.0 /16 In a NAT scheme, are RFC 1918 addresses used on the inside of the network, or on the Internet? They’re used on the inside network. RFC 1918 addresses must not be used on interfaces connected to the Internet. A host on your network has the IP address 10.1.1.1. This address is translated to 210.1.1.1 on your NAT router. Which address is the inside global address?


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The address 210.1.1.1 is the inside global address. The IP address 10.1.1.1 is the inside local address. Your Ethernet0 segment has several hosts that will be using NAT for Internet connectivity. What command must be placed on that Ethernet0 interface? Ip nat inside Your Serial1 interface will be performing network address translation for users on your Ethernet0 interface’s subnet. What command must be placed on the Serial1 interface? Ip nat outside You are using static NAT. What command maps the inside local address 10.1.1.1 to the inside global address 210.5.5.5? Ip nat inside source static 10.1.1.1 210.5.5.5 What command is used to show NAT mappings, both static and dynamic? Show ip nat translations What command is used to show the number of NAT mappings, both static and dynamic? Show ip nat statistics You are going to use a pool of addresses for dynamic NAT. The inside addresses are in the 10.4.4.0 255.255.255.0 network. These addresses will be translated to the range of addresses 210.1.1.7 – 210.1.1.15 with a /24 mask. What three commands will be needed to perform this task? Access-list 5 permit 10.4.4.0 0.0.0.255 Ip nat inside source list 5 pool NATPOOL


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Ip nat pool NATPOOL 210.1.1.7 210.1.1.15 netmask 255.255.255.0 Regarding NAT, what is meant by the term “overloading”? Overloading refers to the use of port numbers to allow the same IP address to be used as the inside global address by multiple inside local addresses. What single word, added to the ip nat inside source command, enabled Port Address Translation? Enter the word “overload” instead of naming a NAT pool of addresses. The outside interface must also be named in this command. Example: ip nat inside source list 5 interface serial1 overload What protocol is used to access a remote networking device? Telnet. Which lines are used for Telnet? The VTY lines are used for Telnet. What must be set on a router to allow remote users to Telnet to it? A password must be set. You want to set your router’s name to “Router1”. What command will do so? Hostname Router1 You want to enter “R2” instead of typing its entire IP address of 2.2.2.2 when using Telnet to connect to that device. What manual command will allow this? Ip host R2 2.2.2.2


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You want to enter “R2” instead of typing its entire IP address of 2.2.22. when using Telnet to connect to that device. What protocol will allow this? DNS will resolve hostnames dynamically. A DNS server must be present on the network for this to occur. When using DNS to resolve hostnames, what command tells the router where the DNS server is? Ip name-server You notice that when you mistype a command, the router tries to resolve it via DNS. What command will prevent this default behavior? No ip domain-lookup What term is used for the process of a router performing routing between VLANs over a single Fast Ethernet connection? Router-on-a-stick. What is the default MTU of an Ethernet port? 1500. What happens to a packet that exceeds the MTU of an Ethernet port? The packet is fragmented. What well-known port number does FTP use? 21.


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Does FTP use TCP or UDP? FTP is TCP-based and is connection-oriented. FTP uses random port numbers as well. What’s always true of one of these random port numbers? The random port number is always greater than 1024. What is the purpose of the “control connection” in FTP? This is the channel that handles the initial request for communication, and any authentication that is in place. Does FTP send data over the control connection, or is a second channel opened? A second channel, the data connection, is opened. What is the major difference between FTP and TFTP? TFTP, Trivial File Transfer Protocol, runs over UDP. It is connectionless, and there is no control connection.


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