PCNE Practice Question: Managing, Monitoring, and Optimising Network Operations
A network engineer is using Connectivity Tests to diagnose a reachability issue between two instances in the same VPC but different subnets. The test indicates that traffic is denied by firewall rules. However, the engineer cannot find any firewall rule denying the traffic. What is a possible explanation?
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 firewall rule is in a different project that is not being checked
If there is an implied deny rule that is not explicitly listed, Connectivity Tests may still show it as the reason. Also, firewall rules are stateful; if return traffic is not matched, it could be denied. But a common oversight is that the firewall rule is in a different project (if using shared VPC) or the rule is disabled.
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 is in a different region
Why it's wrong here
Subnets in same VPC can communicate; region doesn't block traffic.
- ✗
VPC Flow Logs are not enabled
Why it's wrong here
Flow Logs do not affect firewall enforcement.
- ✗
The instances have external IPs
Why it's wrong here
External IPs do not bypass firewall rules.
- ✓
The firewall rule is in a different project that is not being checked
Why this is correct
Correct: In shared VPC, firewall rules may be in the host project, and if not checked, they can cause denial.
Visual reference
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.