Refer to the exhibit. Mutual redistribution is enabled between RIP and EIGRP on R2 and R5. Which configuration resolves the routing loop for the 192.168.1.0/24 network?
For firther Clarification: Answer D according to document (router eigrp 7). However answer A is the only one where the interfaces match up to the diagram.
First off, the exhibit is wrong in that a loop is caused in this scenario. EIGRP has two ways of preventing this loop, 1) Split Horizon and 2) EIGRP External routes have an AD of 170.
IGRP would cause a loop because AD is 100 for both internal and external routes.
Life of the route 192.168.1.0/24
1) R1 advertises 192.168.1.0/24 via RIP with AD 120.
2) R2 and R5 learn the route via their links to R1 on RIP with AD 120
3) R2 and R5 redistribute the route into IGRP outbound of interface S1.
4) R3 and R4 learn the route via their links to R2 and R5 respectively and advertise it to each other, R3 to R4, and R4 to R3
5) R2 and R5 learn the route again via their links to R3 and R4, respectively. Note that this route is now learned via IGRP with an AD of 100 which is preferred over RIP AD 120.
6) Loopty doop.
Solution:
Filter the route from being learned via Interface S1 on R2 and R5.
This question with EIGRP does not make any sense. This scenario does not create a looping.
If you replace EIGRP by IGRP the looping is true, just like the exemplo in this link: https://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/8606-redist.html
With IGRP instead EIGRP, D is right.
Good point! The example from the above article is for IGRP - RIP redistribution. IGRP has AD of 100 for both internal and external routes. So, R2 and R5 are going to prefer the IGRP path for 192.168.1.0/24, and not RIP with AD 120. EIGRP with external AD of 170 won't have this issue. Btw, the article has an example for EIGRP "Example 2". I think that their "Example 2" is not entirely correct.)
I'm glad I wasn't going crazy, I wrote down notes on how the route would be installed in the RIB. R2 and R5 will install the route as RIP AD 120, which will be preferred over EIGRP external AD 170, R3 and R4 will not have a cause for Loop as they will learn it through R2 and R5 respectively with AD 170.
No loop here.
Example is taken from the cisco document linked by BECAUSE:
https://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/8606-redist.html
"[R2 and R5] are told that they must not learn network 192.168.1.0/24 through the EIGRP updates they receive on their serial 1 interface. Therefore, the only knowledge these routers have for network 192.168.1.0/24 is through RIP from R1."
I agree D
Both R2 and R5 are redistributing the rip route for 192.168.1.0/24. What you want to do is block that route that is being received from R3/R4 and being redistributed back into R2 and R5.
Given answer is correct.
https://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/8606-redist.html
upvoted 2 times
...
This section is not available anymore. Please use the main Exam Page.300-410 Exam Questions
Log in to ExamTopics
Sign in:
Community vote distribution
A (35%)
C (25%)
B (20%)
Other
Most Voted
A voting comment increases the vote count for the chosen answer by one.
Upvoting a comment with a selected answer will also increase the vote count towards that answer by one.
So if you see a comment that you already agree with, you can upvote it instead of posting a new comment.
CiscoTerminator
2 months, 1 week ago[Removed]
9 months, 2 weeks agobk989
1 year, 1 month ago[Removed]
1 year, 9 months agoMalasxd
1 year, 11 months agoHungarianDish_111
1 year, 10 months agoHungarianDish_111
1 year, 10 months ago[Removed]
1 year, 9 months agoHungarianDish_111
1 year, 12 months agoHungarianDish_111
1 year, 12 months agoDUBC89x
2 years, 5 months agoBECAUSE
2 years, 6 months ago