PCNE VPC Network Peering Practice Question
An engineer has set up VPC Network Peering between VPC-A and VPC-B. Both VPCs have non-overlapping CIDR ranges. The peering state is ACTIVE. However, instances in VPC-A cannot reach instances in VPC-B. The engineer verified that firewall rules allow the traffic. What should the engineer check next?
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 subnet routes are exported from VPC-B to VPC-A.
VPC Network Peering requires that subnet routes be exported from the peered VPC. By default, subnet routes are automatically exported, but if the peering configuration was modified (e.g., exportSubnetRoutesWithPublicIp set to false), routes may not be exported. The engineer should verify that VPC-B exports its subnet routes to VPC-A. Option B is incorrect because BGP is not used in VPC peering; Cloud Router is used for Cloud VPN or Dedicated Interconnect, not peering. Option C is incorrect because MTU mismatch is unlikely to cause complete lack of connectivity. Option D is incorrect because the route tables themselves are not the issue; the missing routes are due to export settings, not the presence of route tables.
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 subnet routes are exported from VPC-B to VPC-A.
Why this is correct
Correct. Subnet routes must be exported from VPC-B to VPC-A for peering to work. If not exported, instances in VPC-A cannot reach VPC-B.
- ✗
The BGP session status on the Cloud Router.
Why it's wrong here
Incorrect. BGP sessions on Cloud Router are used for hybrid connectivity (VPN/Direct Connect), not for VPC peering.
- ✗
The MTU size of the instances.
Why it's wrong here
Incorrect. MTU mismatch may cause performance issues but not complete connectivity failure.
- ✗
The route tables for the peered network.
Why it's wrong here
Incorrect. Route tables in VPC-A do not automatically include routes to VPC-B unless subnet routes are exported from VPC-B. The issue is export, not the route table itself.
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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.