Refer to the exhibit. Routers R1 and R2 have established a network adjacency using EIGRP, and both routers are advertising subnets to its neighbor. After issuing the show ip EIGRP topology all-links command in R1, some prefixes are not showing R2 as a successor. Which action resolves the issue?
To resolve the issue where some prefixes are not showing R2 as a successor in the EIGRP topology table, it is necessary to rectify the incorrect router ID in R2. When two EIGRP routers have overlapping router IDs, they might not accept each other's locally generated routes. This can lead to routes being learned but not installed in the topology table under certain circumstances. By assigning unique router IDs to each router, the issue with missing prefixes in the EIGRP topology table should be resolved.
Answer is A Can't be B, because if it has been the case, no route at all from R2 would have been learned Can't be C, because a metric mismatch leads in no neighbor relationship and we have Can't be D, Split horizon is enabled by default and it just avoid sharing the network via a same interface it received. It means i can GET routes from R2 but not just sharing them back to R2 via the same interface.
EIGRP require the K values to match only .. not bandwidth or delay. I think C is a possible answer.
Correct answer is B I have just labbed this up, two EIGRP routers with the same router ID, they did not accept each others locally generated routes, however all other EIGRP learned routes that did not originate from them were accepted It does make sense for the receiving router to feel weird receiving a route with its own router ID as the originating router, as soon as I changed the router ID on one of them, they both accepted each others locally generated routes (installed them in the topology table), changed router ID to match again and the routes disappeared again. The reason some routes shows up according to the question is because those routes were not generated by R2
I didn't get it. The routes do not has R2 as sucessors are directly connected. You cannot change it.
Agree. I do not see any incorrect metrics either. I tried to figure it out in the lab, but information about the topology is missing, and thus I can't conclude to any of the answers. In some topology, not all routes are listed as feasible successors due to split-horizont. (Still we would not disable SH just because of that.) https://community.cisco.com/t5/switching/eigrp-topology-table-all-links/td-p/3179536
I think "C" is the best answer.
Agree with SolidSnake74
as explained by solidsnake74. The best answer is A. B, the router ID is different, otherwise no routes would be learned at all, neighborship forms, but no routes learned. C, no neighborship with an error message pointing out K-value mismatch D, no.
I vote for A
why? please
EIGRP will form adjacency with another router with a matching ID but will not install routes ORIGINATED from that router. It will however install routes that did not originate from that router that it received in the Update.
The Answer is B. Lab'd it. 3 router topology. R1, R2, and R3. R1 and R2 have the same ip addresses as indicated. R2 and R3 have a link between them (201.165.101.1 and .2 respectively. R3 has the 192 addresses on loopback interfaces. When you let EIGRP choose the router-id's all links show up, even the link between R2/R3. When you match the router-id to 1.1.1.1 on R1 and R2, the link between R2 and R3 goes away and you are left with the exact same output that is displayed in the exhibit.
The question implies routes ARE advertised but NOT showing at R1. This indeed implies a overlap in router ID. If the question did NOT state "and both routers are advertising subnets to its neighbor." So, i will go with B on this one. It seems only EXTERNAL routes D EX routes are impacted by overlapping Router ID. See https://community.cisco.com/t5/routing/eigrp-router-id-importance/td-p/1311143
I think A
If two routers have the same router ID, they can become neighbors but some prefixes (specifically external redistributed prefixes) will be missing.
router id R2: 203.0.113.2 (from "sh ip eigrp neigh") router id R1: 172.16.10.1 (from "sh ip eigrp top all") The router ids are different.
router id R2: 203.0.113.2, Doesn't rourter ID it's interface's ip
203.0.113.2 is interface address, not RID