Help with Practice Question

Can someone explain why the answer is D? I have stared at this line by line and tried to see what jumps out as far as that path in the routing table and cannot figure it out on my own.

4. Router1#show ip routeCodes: C-connected, s-static, l –IGRP, R –RIP, M –mobile, B –BGP, D –EIGRP, EX – EIGRP external, O – OSPF, IA –OSPF inter area, EI –OSPF external type 1, E2 –OSPF external type 2, E –EGP, i –IS-IS, L1 –IS-IS level-1, L2 –IS-IS level-2, * -candidate default, U – per-user static route Gateway of last resort is not set R 202.30.8.0 /24[120/1] via 202.30.2.2, 00:00:10, Serial 0 C 202.30.9.0 /24 is directly connected, Serial 1 R 202.30.10.0 /24 [120/7] via 202.30.9.1, 00:00:02, Serial 1 R 202.30.11.0 /24 [120/7] via 202.30.9.1, 00:00:03, Serial 1

C 202.30.1.0 /24 is directly connected, Ethernet 0 C 202.30.2.0 /24 is directly connected, Serial 0 R 202.30.3.0 /24 [120/1] via 202.30.2.2, 00:00:10. Serial 0 R 202.30.4.0 /24 [120/15/ via 202.30.2.2, 00:00:10, Serial 0 R 202.30.5.0 /24 [120/15] via 202.30.2.2, 00:00:10, Serial 0 R 202.30.6.0 /24 [120/15] via 202.30.2.2, 00:00:10, Serial 0 R 202.30.7.0 /24 [120/1] via 202.30.2.2, 00:00:10, Serial 0

You examine the routing table of your router named Router1. This routing table will be send to neighboring routers via broadcasts. Some routes might be discarded and not entered in to the routing tables of the neighboring RIP routers. Which of the following routes would be discarded in this way?

A. R 202.30.8.0/24 [120/1] via 202.30.2.2, 00:00:10, Serial0 B. R 202.30.11.0/24 [120/7] via 202.30.9.1, 00:00:03, Serial1 C. C 202.30.1.0/24 is directly connected, Ethernet0 D. R 202.30.5.0/24 [120/15] via 202.30.2.2, 00:00:10, Serial0

Answer:D

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Comments

2lazybutsmart

The answer is D because the hop-count is 15 and will be 16 (invalid) when the route update reaches the next router. That will cause the router to discard that route.

Remember that RIP uses hop count to determine the wether a route is good or not. The hop-count is incremented on every router that forwards the update. A hop count more than 15 means that route is bad.

That's how RIP poisons routes too. It just advertises it as 16 hops --poof, it's gone from everyones tables.

2lbs.

EdTheLad

The answer is D due to [120/15], 120 is the administative disance of the route which in this case is RIP, 15 is the hop count.Since 15 is the max hop count for rip this is why it gets discarded.
I would suggest next time you post, spend some time making the post readable, if you cant spend a little time on presentation why should others
spend time answering your questions!

Ah well 2lazy got there first!

QUIX0TIC

D. R 202.30.5.0/24 [120/15] via 202.30.2.2, 00:00:10, Serial0 what does a administrative distance of 15 in RIP mean?

QUIX0TIC

Ooops... I had to leave and didnt submit my question. The question is designed to asked the original poster what it meant... not me asking what it means...