- A
Verify that the network path between instances does not have a smaller MTU (e.g., VPN or load balancer)
Correct: Path MTU discovery can reveal smaller MTUs along the path.
- B
Enable Cloud NAT to reduce packet size
Why wrong: Cloud NAT does not affect MTU.
- C
Check the MTU configuration on the instances (default 1460)
Correct: Instances have MTU 1460; if set to 1500, fragmentation may occur.
- D
Use VPC Flow Logs to check for packet drops
Why wrong: Flow Logs capture metadata, not packet drops due to MTU.
- E
Capture packets using tcpdump on the instances to look for fragmentation
Correct: Packet capture can show fragmented packets indicating MTU issues.
Question 289 of 1,000
PCNE Practice Question: Managing, Monitoring, and Optimising Network Operations
This PCNE practice question tests your understanding of managing, monitoring, and optimising network operations. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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)
- ✗
Enable Cloud NAT to reduce packet size
- ✓
Check the MTU configuration on the instances (default 1460)
- ✗
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
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Visual reference
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related PCNE NAT questions on configuration and troubleshooting.
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Managing, Monitoring, and Optimising Network Operations — study guide chapter
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FAQ
Questions learners often ask
What does this PCNE question test?
Managing, Monitoring, and Optimising Network Operations — This question tests Managing, Monitoring, and Optimising Network Operations — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this PCNE question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related PCNE NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Last reviewed: Jul 4, 2026
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.
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