PCNE Implementing Hybrid Interconnectivity Practice Question
A Cloud Router BGP session is flapping. Which TWO actions are appropriate troubleshooting steps?
⚠ Common exam trap
Google Cloud often tests the misconception that increasing bandwidth or recreating attachments resolves BGP flapping, when in fact the issue is typically related to MTU mismatches or BGP timer misconfigurations that affect session stability.
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
✓
Check the MTU size on the VPN tunnel or interconnect.
An MTU mismatch on the VPN tunnel or interconnect can cause packet fragmentation or drops, leading to BGP session flapping. Cloud Router uses Google's internal infrastructure, and if the MTU is set too low, large BGP update packets may be silently discarded, triggering hold timer expiry and session resets. Checking and adjusting the MTU ensures that BGP packets can traverse the path without fragmentation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Check the MTU size on the VPN tunnel or interconnect.
Why this is correct
MTU mismatches can cause packet loss and BGP session drops.
- ✗
Delete and recreate the VLAN attachment.
Why it's wrong here
That is a destructive step; better to check configurations first.
- ✗
Revert all BGP routes to static routes.
Why it's wrong here
This is a drastic measure and not a troubleshooting step.
- ✓
Verify BGP timers and hold time settings.
Why this is correct
Incorrect timers can cause premature session termination.
- ✗
Increase the bandwidth of the interconnect.
Why it's wrong here
Bandwidth does not cause flapping; flapping is usually due to configuration or link stability.
Go deeper
Related to this question
About these practice questions
One of 961 original PCNE practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
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.