IP Routing problems
- 1. If your routing table has a static, a RIP, and an IGRP route to the same network, which route will be used to route packets by default?
Options- A. Any available route
- B. RIP route
- C. Static route
- D. IGRP route
- E. They will all load-balance. Discuss
Correct Answer: Static route
Explanation:
Static routes have an administrative distance of 1 by default. Unless you change this, a static route will always be used over any other found route. IGRP has an administrative distance of 100, and RIP has an administrative distance of 120, by default.
- 2. What command is used to stop RIP routing updates from exiting out an interface but still allow the interface to receive RIP route updates?
Options- A. Router(config-if)# no routing
- B. Router(config-if)# passive-interface
- C. Router(config-router)# passive-interface s0
- D. Router(config-router)# no routing updates Discuss
Correct Answer: Router(config-router)# passive-interface s0
Explanation:
The
(config-router)#passive-interface command stops updates from being sent out an interface, but route updates are still received.
- 3. What is route poisoning?
Options- A. It sends back the protocol received from a router as a poison pill, which stops the regular updates.
- B. It is information received from a router that can't be sent back to the originating router.
- C. It prevents regular update messages from reinstating a route that has just come up.
- D. It describes when a router sets the metric for a downed link to infinity. Discuss
Correct Answer: It describes when a router sets the metric for a downed link to infinity.
Explanation:
Another way to avoid problems caused by inconsistent updates and to stop network loops is route poisoning. When a network goes down, the distance-vector routing protocol initiates route poisoning by advertising the network with a metric of 16, or unreachable (sometimes referred to as infinite).
- 4. Network 206.143.5.0 was assigned to the Acme Company to connect to its ISP. The administrator of Acme would like to configure one router with the commands to access the Internet. Which commands could be configured on the Gateway router to allow Internet access to the entire network?
- Gateway(config)# ip route 0.0.0.0 0.0.0.0 206.143.5.2
- Gateway(config)# router rip
- Gateway(config-router)# network 206.143.5.0
- Gateway(config-router)# network 206.143.5.0 default
Options- A. 1 only
- B. 3 only
- C. 1, 2 and 4
- D. 1 and 4 Discuss
Correct Answer: 1 and 4
Explanation:
There are actually three different ways to configure the same default route, but only two are shown in the answer. First, you can set a default route with the
0.0.0.0 0.0.0.0 mask and then specify the next hop, as in option A. Or you can use
0.0.0.0 0.0.0.0 and use the exit interface instead of the next hop. Finally, you can use option D with the
ip default-network command.
- 5. Which of the following is true regarding RIPv2?
Options- A. It has a lower administrative distance than RIPv1.
- B. It converges faster than RIPv1.
- C. It has the same timers as RIPv1.
- D. It is harder to configure than RIPv1. Discuss
Correct Answer: It has the same timers as RIPv1.
Explanation:
RIPv2 is pretty much just like RIPv1. It has the same administrative distance and timers and is configured just like RIPv1.
- 6. What is split horizon?
Options- A. Information about a route should not be sent back in the direction from which the original update came.
- B. It splits the traffic when you have a large bus (horizon) physical network.
- C. It holds the regular updates from broadcasting to a downed link.
- D. It prevents regular update messages from reinstating a route that has gone down. Discuss
Correct Answer: Information about a route should not be sent back in the direction from which the original update came.
Explanation:
A split horizon will not advertise a route back to the same router it learned the route from.
- 7. You have the following routing table. Which of the following networks will not be placed in the neighbor routing table?
R 192.168.30.0/24 [120/1] via 192.168.40.1, 00:00:12, Serial0 C 192.168.40.0/24 is directly connected, Serial0 172.16.0.0/24 is subnetted, 1 subnets C 172.16.30.0 is directly connected, Loopback0 R 192.168.20.0/24 [120/1] via 192.168.40.1, 00:00:12, Serial0 R 10.0.0.0/8 [120/15] via 192.168.40.1, 00:00:07, Serial0 C 192.168.50.0/24 is directly connected, Ethernet0
Options- A. 172.16.30.0
- B. 192.168.30.0
- C. 10.0.0.0
- D. All of them will be placed in the neighbor routing table. Discuss
Correct Answer: 10.0.0.0
Explanation:
The network 10.0.0.0 cannot be placed in the next router's routing table because it already is at 15 hops. One more hop would make the route 16 hops, and that is not valid in RIP networking.
- 8. A network administrator views the output from the show ip route command. A network that is advertised by both RIP and IGRP appears in the routing table flagged as an IGRP route. Why is the RIP route to this network not used in the routing table?
Options- A. IGRP has a faster update timer.
- B. IGRP has a lower administrative distance.
- C. RIP has a higher metric value for that route.
- D. The IGRP route has fewer hops. Discuss
Correct Answer: IGRP has a lower administrative distance.
Explanation:
RIP has an administrative distance (AD) of 120, while IGRP has an administrative distance of 100, so the router will discard any route with a higher AD than 100.
- 9. Two connected routers are configured with RIP routing. What will be the result when a router receives a routing update that contains a higher-cost path to a network already in its routing table?
Options- A. The updated information will be added to the existing routing table.
- B. The update will be ignored and no further action will occur.
- C. The updated information will replace the existing routing table entry.
- D. The existing routing table entry will be deleted from the routing table and all routers will exchange routing updates to reach convergence. Discuss
Correct Answer: The update will be ignored and no further action will occur.
Explanation:
When a routing update is received by a router, the router first checks the administrative distance (AD) and always chooses the route with the lowest AD. However, if two routes are received and they both have the same AD, then the router will choose the one route with the lowest metrics, or in RIP's case, hop count.
- 10. Which two of the following are true regarding the distance-vector and link-state routing protocols?
- Link state sends its complete routing table out all active interfaces on periodic time intervals.
- Distance vector sends its complete routing table out all active interfaces on periodic time intervals.
- Link state sends updates containing the state of its own links to all routers in the internetwork.
- Distance vector sends updates containing the state of its own links to all routers in the internetwork.
Options- A. 1 only
- B. 3 only
- C. 2 and 3 only
- D. None of the above Discuss
Correct Answer: 2 and 3 only
Explanation:
The distance-vector routing protocol sends its complete routing table out all active interfaces at periodic time intervals. Link-state routing protocols send updates containing the state of its own links to all routers in the internetwork.
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