CCNA CAT 21. Which of the following best describes the main function of OSI Layer 1 protocols?(1 MKS)a. Framing b. Delivery of bits from one device to another c. Addressing d. Local Management Interface (LMI) e. DLCI2. Which of the following typically connects to a four-wire line provided by a telco? (1 MKS)a. Router serial interface b. CSU/DSU c. Transceiver d. Switch serial interface

3. Which of the following typically connects to a V.35 or RS-232 end of a cable whencabling a line leased? (1 MKS)a. Router serial interface b. CSU/DSU c. Transceiver d. Switch serial interface

4. On a point-to-point WAN link using a leased line between two routers locatedhundreds of miles apart, what devices are considered to be the DTE devices? (1 MKS)a. Routers b. CSU/DSUc. The central office equipment d. A chip on the processor of each routere. None of these answers are correct.

5. Which of the following functions of OSI Layer 2 is specified by the protocol standard for PPP, but is implemented with a Cisco proprietary header field for HDLC? (1 MKS)a. Framing b. Arbitration c. Addressing d. Error detection e. Identifying the type of protocol that is inside the frame

6. Imagine that Router1 has three point-to-point serial links, one link each to three remoterouters. Which of the following is true about the required HDLC addressing atRouter1? (1 MKS)a. Router1 must use HDLC addresses 1, 2, and 3.b. Router1 must use any three unique addresses between 1 and 1023.c. Router1 must use any three unique addresses between 16 and 1000.d. Router1 must use three sequential unique addresses between 1 and 1023.e. None of these answers are correct.

7. What is the name of the Frame Relay field used to identify Frame Relay virtualcircuits? (1 MKS)a. Data-link connection identifierb. Data-link circuit identifier

c. Data-link connection indicatord. Data-link circuit indicatore. None of these answers are correct.

8. Which of the following is true about Frame Relay virtual circuits (VCs)? (1 MKS)a. Each VC requires a separate access link.b. Multiple VCs can share the same access link.c. All VCs sharing the same access link must connect to the same router on theother side of the VC.d. All VCs on the same access link must use the same DLCI.

9. Which of the following are functions of OSI Layer 3 protocols? (2 MKS)a. Logical addressing b. Physical addressing c. Path selection d. Arbitration e. Error recovery

10. Imagine that PC1 needs to send some data to PC2, and PC1 and PC2 are separated byseveral routers. What are the largest entities that make it from PC1 to PC2? (2 MKS)a. Frame b. Segment c. Packet d. L5 PDU e. L3 PDU f. L1 PDU

11. Imagine a network with two routers that are connected with a point-to-point HDLC serial link. Each router has an Ethernet, with PC1 sharing the Ethernet with Router1,and PC2 sharing the Ethernet with Router2. When PC1 sends data to PC2, which of the following is true? (1 MKS)a. Router1 strips the Ethernet header and trailer off the frame received from PC1,never to be used again.b. Router1 encapsulates the Ethernet frame inside an HDLC header and sends theframe to Router2, which extracts the Ethernet frame for forwarding to PC2.

c. Router1 strips the Ethernet header and trailer off the frame received from PC1,which is exactly re-created by R2 before forwarding data to PC2. (1 MKS)d. Router1 removes the Ethernet, IP, and TCP headers and rebuilds the appropriateheaders before forwarding the packet to Router2.

12. Which of the following are valid Class C IP addresses that can be assigned to hosts? (1 MKS)a. 1.1.1.1 b. 200.1.1.1 c. 128.128.128.128 d. 224.1.1.1 e. 223.223.223.255

13. What is the range of values for the first octet for Class A IP networks? (1 MKS)

14. PC1 and PC2 are on two different Ethernets that are separated by an IP router. PC1’sIP address is 10.1.1.1, and no subnetting is used. Which of the following addressescould be used for PC2?a. 10.1.1.2 b. 10.2.2.2 c. 10.200.200.1 d. 9.1.1.1 e. 225.1.1.1 f. 1.1.1.1

15. Each Class B network contains how many IP addresses that can be assigned to hosts? (1 MKS)65,53416. Each Class C network contains how many IP addresses that can be assigned to hosts? (1 MKS)25416. Which of the following does a router normally use when making a decision about routing TCP/IP packets? (1 MKS)a. Destination MAC address b. Source MAC address c. Destination IP address d.Source IP address e. Destination MAC and IP address

17. Which of the following are true about a LAN-connected TCP/IP host and its IP routing (forwarding) choices? (2 MKS)a. The host always sends packets to its default gateway.b. The host sends packets to its default gateway if the destination IP address is in adifferent class of IP network than the host.c. The host sends packets to its default gateway if the destination IP address is in adifferent subnet than the host.d. The host sends packets to its default gateway if the destination IP address is in the same subnet as the host.

18. Which of the following are functions of a routing protocol? (2 MKS)a. Advertising known routes to neighboring routers.b. Learning routes for subnets directly connected to the router.c. Learning routes, and putting those routes into the routing table, for routes advertised to the router by its neighboring routers.d. To forward IP packets based on a packet’s destination IP address.

19. Which of the following protocols allows a client PC to discover the IP address of another computer based on that other computer’s name? (1 MKS)a. ARP b. RARP c. DNS d. DHCP

20. Which of the following protocols allows a client PC to request assignment of an IP address as well as learn its default gateway? (1 MKS)

a. ARP b. RARP c. DNS d. DHCP

21. PC1 is using TCP and has a window size of 4000. PC1 sends four segments to PC2 with 1000 bytes of data each, with sequence numbers 2000, 3000, 4000, and 5000. PC2 replies with an acknowledgment number of 5000. What should PC1 do next? (1 MKS)a. Increase its window to 5000 or more segmentsb. Send the next segment, with sequence number 6000c. Resend the segment whose sequence number was 5000d. Resend all four previously sent segments

22. Imagine a network with two routers that are connected with a point-to-point HDLC serial link. Each router has an Ethernet, with PC1 sharing the Ethernet with Router1, and PC2 sharing the Ethernet with Router2. When PC1 sends data to PC2, which of the following is true? (2 MKS)a. Router1 strips the Ethernet header and trailer off the frame received from PC1, never to be used again.b. Router1 encapsulates the Ethernet frame inside an HDLC header and sends the frame to Router2, which extracts the Ethernet frame for forwarding to PC2.c. Router1 strips the Ethernet header and trailer off the frame received from PC1, which is exactly re-created by R2 before forwarding data to PC2.d. Router1 removes the Ethernet, IP, and TCP headers and rebuilds the appropriate headers before forwarding the packet to Router2.

23.Which of the following functions is performed by both TCP and UDP?a. Windowing b. Error recovery c. Multiplexing using port numbers d. Routing e. Encryption f. Ordered data transfer