PCNE Implementing Hybrid Interconnectivity Practice Question
A company is using Cloud VPN with BGP to connect their on-premises network to Google Cloud. They have two VPN tunnels from two different on-premises VPN gateways to a single Cloud VPN gateway. They notice that during maintenance on one on-premises gateway, traffic fails over to the other tunnel, but after the maintenance, traffic does not fail back. What is the most likely cause?
⚠ Common exam trap
Test-takers frequently assume failback is automatic with BGP, but without explicit local preference tuning, BGP will not prefer the primary tunnel after recovery, leading to asymmetric traffic or persistent backup path usage.
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 local preference on the primary tunnel is not higher than the backup tunnel
B is correct because BGP local preference is used to influence outbound traffic path selection. If the primary tunnel's local preference is not higher than the backup tunnel, BGP will not prefer the primary route after the backup session recovers, causing traffic to remain on the backup tunnel. This is a classic BGP route selection behavior where the highest local preference wins.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Only one VPN tunnel can be active at a time
Why it's wrong here
Cloud VPN supports multiple tunnels.
- ✓
The BGP local preference on the primary tunnel is not higher than the backup tunnel
Why this is correct
Without a higher local preference, the backup tunnel remains preferred after failover.
- ✗
Cloud VPN gateway does not support BGP
Why it's wrong here
Cloud VPN gateway supports BGP.
- ✗
The backup tunnel does not have a valid BGP session
Why it's wrong here
Failover works, so BGP session is valid.
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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.