PCNE Practice Question: Managing, Monitoring, and Optimising Network Operations
A company is experiencing packet loss between two Compute Engine instances in different zones within the same region. They suspect MTU issues. Which three actions should they take to diagnose and resolve? (Choose three.)
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
✓
Verify that the network path between instances does not have a smaller MTU (e.g., VPN or load balancer)
Check the MTU settings on the instances (default 1460 for GCP). Use packet capture to see if fragmentation is occurring. Ensure that the path MTU is consistent (e.g., between VMs and any load balancers). VPC Flow Logs do not show MTU. Cloud NAT is not relevant. Connectivity Tests do not test MTU.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Verify that the network path between instances does not have a smaller MTU (e.g., VPN or load balancer)
Why this is correct
Correct: Path MTU discovery can reveal smaller MTUs along the path.
- ✗
Enable Cloud NAT to reduce packet size
Why it's wrong here
Cloud NAT does not affect MTU.
- ✓
Check the MTU configuration on the instances (default 1460)
Why this is correct
Correct: Instances have MTU 1460; if set to 1500, fragmentation may occur.
- ✗
Use VPC Flow Logs to check for packet drops
Why it's wrong here
Flow Logs capture metadata, not packet drops due to MTU.
- ✓
Capture packets using tcpdump on the instances to look for fragmentation
Why this is correct
Correct: Packet capture can show fragmented packets indicating MTU issues.
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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.