hardMultiple ChoiceObjective-mapped
300-410 Practice Question: Is troubleshooting a BGP session that is not…
A network engineer is troubleshooting a BGP session that is not establishing. The routers are connected via a Layer 3 switch. BFD is configured for BGP. The engineer checks the BFD session and sees it is 'Down'. The BGP configuration appears correct. The interface between the routers is up/up. What is the most likely 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 BGP neighbor is not directly connected; BFD requires a directly connected interface or a static route pointing to the neighbor's IP.
BFD sessions require that the destination IP address be reachable via a directly connected interface or a static route. If the BGP neighbor is not directly connected (e.g., via a loopback), BFD may fail if the next hop is not directly connected or if there is a routing issue.
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 BGP neighbor is not directly connected; BFD requires a directly connected interface or a static route pointing to the neighbor's IP.
Why this is correct
BFD sessions over multihop BGP require special configuration (bfd all-interfaces under BGP) and a route to the neighbor; if the neighbor is not directly connected, BFD will fail without proper setup.
- ✗
The Layer 3 switch is not configured for BFD, causing it to drop BFD packets.
Why it's wrong here
The switch does not need to run BFD; it only forwards packets. BFD packets are UDP and should be forwarded normally.
- ✗
The BGP session is using EBGP multihop, and the TTL is set to 1.
Why it's wrong here
If TTL is 1, BGP packets would not reach the neighbor, but BFD packets would still be sent; the BFD session would still attempt to form.
- ✗
The interface is configured with 'bfd interval 50 min_rx 50 multiplier 3' but the neighbor is not configured for BFD.
Why it's wrong here
If the neighbor is not configured for BFD, the BFD session will not form, but the engineer would see the session as 'Down' with no configuration on the neighbor.
Go deeper
Related to this question
About these practice questions
Courseiva writes every 300-410 question from scratch — 1,966 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
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.