PCNE Configuring Network Services Practice Question
A company uses Cloud NAT for outbound internet access. Engineering notices that some VM instances fail to connect to external services during peak hours. The network engineer suspects port exhaustion. Which action would best mitigate this issue?
⚠ Common exam trap
Google Cloud often tests the misconception that reducing NAT gateways or changing NAT type solves port exhaustion, when the actual solution is increasing the number of NAT IP addresses to expand the available port range.
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
✓
Increase the number of NAT IP addresses assigned to the NAT gateway.
Port exhaustion occurs when the NAT gateway runs out of available source ports to map outbound connections. Increasing the number of NAT IP addresses assigned to the gateway multiplies the available port range (each IP provides 64,512 ports), directly alleviating port exhaustion during peak traffic. This is the standard mitigation for port exhaustion in Cloud NAT.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Change the NAT type from standard to public.
Why it's wrong here
NAT types (public, private) do not affect port capacity.
- ✗
Enable TCP keepalive on the NAT gateway.
Why it's wrong here
TCP keepalive helps release idle connections but does not increase the total number of available ports.
- ✗
Reduce the number of NAT gateways in the region.
Why it's wrong here
Reducing NAT gateways decreases port capacity and makes exhaustion worse.
- ✓
Increase the number of NAT IP addresses assigned to the NAT gateway.
Why this is correct
More NAT IPs provide additional source ports, alleviating exhaustion.
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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.