PCNE Practice Question: Designing, Planning, and Prototyping a GCP Network
A company uses a Shared VPC with a host project and multiple service projects. They have deployed Cloud NAT in the host project's network to provide internet access for service project instances. The Cloud NAT is configured to use a network tag 'nat'. Instances in service projects that have the tag 'nat' can reach the internet. A new service project is added and its instances are created with the same tag 'nat' in a subnet in europe-west1. However, these instances cannot reach the internet. Other service project instances with the tag 'nat' in us-central1 work fine. The Cloud NAT is deployed in us-central1. What is the most likely cause?
⚠ Common exam trap
Many candidates assume Cloud NAT is a global resource or that network tags alone ensure connectivity, overlooking the critical regional scope of Cloud NAT and the fact that it must be deployed in the same region as the instances it serves.
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 Cloud NAT is not in the same region as the new service project's instances.
Cloud NAT is a regional resource; it only provides outbound internet access to instances within the same region. Since the Cloud NAT is deployed in us-central1, instances in europe-west1 cannot use it, regardless of their network tag. The instances in the new service project must have a Cloud NAT deployed in europe-west1 to reach the internet.
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 Cloud NAT's UDP timeout is too short.
Why it's wrong here
Timeout would not prevent all connectivity.
- ✗
The firewall rules in the host project block traffic from the new service project's subnets.
Why it's wrong here
Firewall rules are not the issue; the region mismatch is.
- ✓
The Cloud NAT is not in the same region as the new service project's instances.
Why this is correct
Cloud NAT only works for instances in its region.
- ✗
The new service project's instances are not tagged with 'nat'.
Why it's wrong here
They are tagged as stated.
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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.