hardMultiple ChoiceObjective-mapped
300-410 R1 and R2 are eBGP peers Practice Question
R1 and R2 are eBGP peers. R1 advertises a prefix 172.16.1.0/24 with AS_PATH 65001 65002. R2 receives the prefix and its BGP table shows AS_PATH 65001 65002. R2 has a route-map applied inbound that sets local-preference 150 for routes with AS_PATH containing 65002. R2 also has another eBGP peer R3 that advertises the same prefix with AS_PATH 65001 65003. R2's BGP best path selection chooses the path via R3 because of shorter AS_PATH length (2 vs 3). However, the network engineer expects the path via R1 to be preferred due to the higher local-preference. 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
✓
The route-map applied inbound on R2 from R1 has a match ip address prefix-list that does not include 172.16.1.0/24, so local-preference is not set.
Local-preference is evaluated before AS_PATH length in BGP best path selection. If the local-preference is set to 150 on the path via R1, it should be preferred over the path via R3 (which likely has default local-preference 100). The fact that R2 chooses R3 indicates that the local-preference was not applied correctly. The root cause is that the route-map is applied inbound on R2 from R1, but the route-map may have a match clause that does not match the prefix, or the set local-preference command is missing. In this scenario, the route-map is applied but the set local-preference is not executed because the match condition fails (e.g., match ip address prefix-list that does not include 172.16.1.0/24).
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The route-map applied inbound on R2 from R1 has a match ip address prefix-list that does not include 172.16.1.0/24, so local-preference is not set.
Why this is correct
If the match condition fails, the set commands are not executed, and the default local-preference (100) applies.
- ✗
AS_PATH length is always preferred over local-preference in BGP best path selection.
Why it's wrong here
Local-preference is evaluated before AS_PATH length.
- ✗
The route-map should be applied outbound on R1 instead.
Why it's wrong here
Local-preference is typically set inbound on the receiving router.
- ✗
R2's BGP table shows the local-preference as 150 for the path via R1, but the best path selection ignores it due to a bug.
Why it's wrong here
If local-preference were 150, it would be preferred. The show output would confirm the actual local-preference.
Go deeper
Related to this question
Learn chapter
Introduction to ENARSI Exam and Network Fundamentals
Key term
BGP Prefix Filtering
BGP Prefix Filtering is the practice of controlling which network routes (prefixes) a router accepts or advertises to its BGP neighbors, preventing unwanted or harmful routes from spreading across the internet.
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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.