PCNE Practice Question: Managing, Monitoring, and Optimising Network Operations
A company has a VPC with a Cloud Router using BGP to advertise prefixes to an on-premises network. The BGP session keeps flapping. What is a 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
✓
There is an MTU mismatch causing packet drops
MTU mismatch can cause packets to be dropped, leading to BGP session instability. Ensure consistent MTU across the path.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
There is an MTU mismatch causing packet drops
Why this is correct
Correct: MTU mismatch can cause BGP keepalive drops, leading to flapping.
- ✗
VPC Flow Logs are enabled on the subnet
Why it's wrong here
Flow Logs do not affect BGP.
- ✗
The firewall rules are blocking BGP traffic
Why it's wrong here
Firewall rules would prevent BGP from establishing at all.
- ✗
The Cloud Router is configured with the wrong ASN
Why it's wrong here
Wrong ASN would prevent session establishment, but not flapping.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCNE practice question is part of Courseiva's free Google Cloud 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 PCNE exam.