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300-410 Practice Question: An engineer is troubleshooting a BGP peering…
An engineer is troubleshooting a BGP peering issue between two routers, R1 and R2, connected via a serial link. The BGP session is established, but routes are not being exchanged. The engineer checks the BGP configuration and sees that both routers have the 'neighbor' commands correctly configured. The output of 'show ip bgp summary' shows the session is in the Established state, but the prefix counts are zero. 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
✓
Neither router has any network statements or redistribution commands configured to inject prefixes into BGP.
If the BGP session is established but no prefixes are exchanged, the most common cause is that there are no networks configured under the BGP process or no redistribution. Alternatively, outbound filters could be blocking all prefixes. The stem says routes are not being exchanged, so the issue is on the advertisement side.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Neither router has any network statements or redistribution commands configured to inject prefixes into BGP.
Why this is correct
Correct because BGP only advertises prefixes that are explicitly injected via network statements, redistribution, or aggregation.
- ✗
The BGP session is using MD5 authentication, but the passwords do not match.
Why it's wrong here
Incorrect because mismatched MD5 passwords would prevent the session from establishing, not cause zero prefixes.
- ✗
The routers have mismatched BGP versions.
Why it's wrong here
Incorrect because mismatched versions would cause negotiation issues or session reset, not an established session with zero prefixes.
- ✗
The update-source command is missing, causing the session to use the wrong interface.
Why it's wrong here
Incorrect because the session is established, so the update-source is working; missing update-source would not cause zero prefixes.
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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.