PCNE Implementing a Virtual Private Cloud Practice Question
A network engineer is configuring VPC peering between two VPCs in the same project. The peering status is ACTIVE, but instances in one VPC cannot reach instances in the other VPC using internal IPs. The firewall rules are default (ingress deny all). 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
✓
The engineer forgot to add firewall rules to allow traffic from the peer range.
Default firewall rules deny all ingress, so even with peering, traffic is blocked unless allow rules are added.
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 VPCs use different routing modes.
Why it's wrong here
Routing mode affects route propagation but not basic connectivity; with ACTIVE peering, routes are exchanged.
- ✗
The IAM permissions for the peering are missing.
Why it's wrong here
IAM permissions are not needed for existing peering connections in the same project.
- ✗
The VPCs have overlapping subnet CIDR ranges.
Why it's wrong here
Overlapping subnets would cause the peering to be INACTIVE.
- ✓
The engineer forgot to add firewall rules to allow traffic from the peer range.
Why this is correct
Firewall rules are required to allow ingress traffic from the peered network.
Go deeper
Related to this question
About these practice questions
Courseiva writes every PCNE question from scratch — 961 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. 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.