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300-410 R1 and R2 are iBGP peers in AS 65001 Practice Question
R1 and R2 are iBGP peers in AS 65001. R1 has: neighbor 10.1.1.2 next-hop-self. R2 advertises a prefix 10.0.0.0/8 with next-hop 10.1.1.2. R1 receives the prefix and changes the next-hop to 10.1.1.1 (its own IP) due to next-hop-self. R1 then advertises this prefix to its eBGP peer R3 in AS 65002. R3 receives the prefix with next-hop 10.1.1.1. R3 has a static route to 10.1.1.0/24 via its interface to R1. However, R3 cannot reach 10.0.0.0/8 because R1 does not have a route to 10.0.0.0/8 in its routing table. What is the root cause?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
R1 does not have a route to 10.0.0.0/8 in its routing table because the BGP route is not installed due to next-hop unreachable or administrative distance conflict.
R1 uses next-hop-self to change the next-hop to its own IP, but R1 must have a valid route to the prefix in its routing table to forward traffic. If R1 does not install the BGP route (e.g., because it is not the best path due to a higher metric or because the next-hop is unreachable), then R1 will not have a route to 10.0.0.0/8 in its routing table, and packets sent to R1 for that prefix will be dropped. The root cause is that R1 does not have the prefix installed in its routing table, possibly because it learned it from R2 but the next-hop (10.1.1.2) is not reachable in R1's routing table, or because R1 has a higher administrative distance route that overrides.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
R1 does not have a route to 10.0.0.0/8 in its routing table because the BGP route is not installed due to next-hop unreachable or administrative distance conflict.
Why this is correct
R1 must have the prefix in its routing table to forward traffic; otherwise, it will drop packets.
- ✗
R3 should use next-hop-self to R1.
Why it's wrong here
R3 is the receiver; next-hop-self is on the advertising router.
- ✗
The next-hop-self command on R1 is misconfigured; it should be on R2.
Why it's wrong here
next-hop-self on R1 is correct for changing next-hop to R1.
- ✗
R1's BGP table shows the prefix with next-hop 10.1.1.1, but that is the next-hop after next-hop-self; the issue is that R1 did not originate the route.
Why it's wrong here
Origination is not required; installation in routing table is.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 300-410 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 300-410 exam.