Question 1 | Which attribute of a Cisco-supported routing protocol makes it capable of rapidly learning about modifications to the network topology? |
A1: | Answer B is correct. Flash updates send asynchronous responses to changes in the network topology. Answer A is incorrect because hold-downs are a state into which routers are placed to purge the network of bad information. Answer C is incorrect because AD numbers simply rate the trustworthiness of the source of routing data. Answer D is incorrect because classful routing pertains to the lack of prefix length information in the routing protocol header. |
Question 2 | Which of the following statements best describes the reason a distance vector protocol takes longer to converge than other routing protocols? -
A. While in a state of hold-down, distance vector protocols do not accept updated route information concerning a particular route unless the update has a better metric value. -
B. Distance vector protocols actually converge more quickly than most other routing protocols. -
C. Distance vector protocols take longer to converge because they use only classful addressing schemes. -
D. Convergence time is a router hardware issue and has little to do with the routing protocol algorithm being implemented. |
A2: | Answer A is correct. Hold-down timers help prevent bad information from propagating through a distance vector area to prevent loops . This can add to the total convergence time because distance vector protocols do not route updates unless the update has a better metric value than the one previously stored. Answer B is incorrect because the opposite is true. Answer C is incorrect because some distance vector protocols, such as RIPv2 and IGRP, can use classless addressing. Answer D is incorrect because, although router hardware is a factor, the routing algorithm and other mechanisms are the key contributors to convergence. |
Question 3 | | What is the default maximum hop count metric for the IGRP routing protocol? | -
A. 255 -
B. 150 -
C. 100 -
D. 15 |
A3: | Answer C is correct. Although the maximum hop count for IGRP is configurable to 255, the default maximum hop count is 100. Therefore, answer A is incorrect yet tricky. Answer B is incorrect, and answer D is the maximum hop count for the RIP routing protocol. |
Question 4 | Which of the following routing protocols implements broadcast packets to disseminate topology update information throughout an internetwork? (Choose two.) -
A. EIGRP -
B. IGRP -
C. OSPF -
D. RIPv1 |
A4: | Answers B and D are correct. IGRP and RIPv1 are distance vector protocols that use a Bellman-Ford algorithm and broadcast update packets to their neighbors. Answer A is incorrect because EIGRP implements a hybrid link-state method for more rapid convergence. Answer C is incorrect because it is a link-state routing protocol that typically uses multicasting to designated routers as opposed to broadcasting. |
Question 5 | Which of the following routing protocols support variable-length subnet masking for Layer 3 addressing schemes? (Choose two.) -
A. EIGRP -
B. IGRP -
C. RIPv1 -
D. RIPv2 |
A5: | Answers A and D are correct. EIGRP and RIPv2 are both capable of specifying a different subnet mask for the same network number on different subnets. Answers B and C are incorrect because IGRP and RIPv1 are classful routing protocols and do not carry information about the prefix length. |
Question 6 | Which of the following are valid metrics used by routing protocols? (Choose all that apply.) -
A. Reliability -
B. Delay -
C. Bandwidth -
D. Trustworthiness |
A6: | Answers A, B, and C are correct. The valid routing metrics that were covered in this chapter include path length, reliability, delay, bandwidth, load, and cost. Answer D is incorrect because, trustworthiness is the measurement designated by the administrative distance (AD), not a routing metric. |
Question 7 | Which one of the following statements best describes the difference between static and dynamic routing? -
A. The dominant routing algorithms used today are static as opposed to dynamic because they better adapt to changing network conditions by analyzing incoming routing updates. -
B. Dynamic routing is always preferred over static routing, especially in environments in which network traffic is relatively predictable and network design is fairly simple. -
C. Dynamic routing is configured by a network administrator and cannot self-adjust to topology changes, whereas static routing adjusts to topology changes by analyzing incoming routing updates without human intervention. -
D. Static routing is configured by a network administrator and cannot self-adjust to topology changes, whereas dynamic routing adjusts to topology changes by analyzing incoming routing updates without human intervention. |
A7: | Answer D is correct. One of the advantages of static routing is the level of security and control that comes from manual administrative configuration. Answer A is incorrect because the dominant routing protocols in use are dynamic and because static protocols do not analyze incoming routing updates. Answer B is incorrect because this is actually a scenario in which static routes are often used rather than dynamic routing. Answer C is incorrect because it is the opposite of the correct answer. |
Question 8 | Which of the following protocols are classified as link-state because they exhibit link-state characteristics? (Choose all that apply.) -
A. IGRP -
B. OSPF -
C. IS-IS -
D. EIGRP |
A8: | Answers B, C, and D are correct. OSPF, IS-IS, and EIGRP are all technically link-state routing protocols. OSPF uses the Dijkstra algorithm, IS-IS uses the IS-IS algorithm, and EIGRP uses the DUAL algorithm. Answer A is incorrect because IGRP uses a distance vector algorithm. |
Question 9 | To avert routing loops and preserve bandwidth when sending routing updates, which mechanism prevents a network entry from being forwarded out on the same interface on which it was learned? -
A. Split horizon -
B. Broadcast update -
C. Triggered update -
D. Count to infinity |
A9: | Answer A is correct. Split horizon is a mechanism that keeps information from exiting a router interface that was learned on that same interface. It is helpful for preventing loops and conserving precious bandwidth. Answer B is incorrect because a broadcast update is a data packet advertised to all nodes on a network. Answer C is incorrect because a triggered update is a special packet generated when a network event occurs. Although a loop prevention mechanism, answer D is incorrect because count to infinity relates to maximum hop count. |
Question 10 | While observing the entries in the routing table, you notice that some of the entries seem a little suspect. Which command can you run to refresh the routing table? -
A. Router>clear ip route -
B. Router#clear ip route -
C. Router>clean ip route -
D. Router#clean ip route |
A10: | Answer B is correct. This is a tricky question that is actually common to Cisco-type exams because it tests two elements of knowledge: the correct syntax and the proper command-mode prompt. If the information in the routing table seems outdated , you can refresh the table by issuing the clear ip route command from the Cisco IOS privileged EXEC prompt. Answer A is incorrect because it is the USER mode prompt. Answer C is the incorrect prompt and command. The clean command is not a valid Cisco IOS command. Answer D is incorrect because it is the correct prompt but the wrong command. |