Exam 300-410 topic 1 question 223 discussion

In Cisco devices, split horizon is always used along with poison reverse (via the command “ip split-horizon”) so in this question split horizon is already turned on. To prevent loop we can only use route filtering.

A is corerct

Poison Reverse is automatically enabled with Split Horizon, you cannot manually enable Poison Reverse. So if the question indicates a loop occurs while Poison Reverse is enabled, then A is not the right answer. Also, all the neighbors are form through different interfaces so the concept of SH doesn't apply anyways, it's only for multipoint interfaces e.g. DMVPN. We don't know which one is R3 to say stub receive-only can avoid the loop, even though it could help. Route tagging works with redistribution so it's not the right answer. Route filtering is the only answer I can think it's right, you can set up a prefix list and filter out routes coming from a neighbor and avoid loops.

I would choose A as my answer by checking other sites. Maybe Cisco is not getting to technical in this question regarding the nature of the poison reverse nature with the split horizon feature

if the Poison reverse is enable in this case and split horizont Never advertise a route out of the interface through which it was learned, the route is advertise in otrer interface so route filtering is the best answer D.

A is the correct answer

Split harizon is enable to prevent loop in EIGRP

It's the correct answer, review the document provided by HungarianDish. Both Split horizon and poison reverse works together for resolve this issue

https://notes.networklessons.com/eigrp-split-horizon-vs-poison-reverse

Split horizon is always used with poison reverse in cisco devices. therefore, the only solution is route filtering.

I thinks it's "A". Split Horizon, Poison reverse and feaseble condition are the mechanisms EIGRP uses to prevents loops.

EIGRP combines poison reverse and split horizon to help prevent routing loops. So, if the question is seeking some general answer, then probably it is "A". Further information (about the loop or about the design) is required to give an accurate answer.

The question is based on this cisco document: https://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/16406-eigrp-toc.html#anc21

B) stub receive-only -> I would not consider it as a loop prevention mechanism, so for me this answer is excluded. It prevents Stuck In Active. https://networklessons.com/eigrp/eigrp-stub-explained https://networklessons.com/eigrp/eigrp-queries-and-stuck-in-active https://www.geeksforgeeks.org/configuring-eigrp-stub-in-cisco/

Topology can be viewed in other dumps: https://vceguide.com/which-action-prevents-the-loop-between-r1-r2-and-r3/

First who is R1, R2, R3 and R4, second split horizon has nothing to do here because routers are not sending routes back from int. it was learned. I think B is the correct one on this case.

i think the given answer is correct.