PCNE Implementing VPC Instances Practice Question
A network engineer wants to restrict access to a Cloud Storage bucket from only a specific set of Compute Engine instances in a VPC. The instances have no external IPs. What is the most effective way to enforce this restriction?
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
✓
Enable Private Google Access on the subnet and use VPC Service Controls with a service perimeter that includes the VPC and the Cloud Storage bucket.
Using Private Google Access with Private Service Connect allows instances to reach Google APIs via internal IPs. By using VPC Service Controls, you can create a service perimeter that restricts access to the Cloud Storage bucket from the specific VPC and projects. This provides a defense-in-depth approach.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Assign a unique service account to the instances and use IAM conditions to allow the service account access to the bucket only when connecting from the VPC network.
Why it's wrong here
IAM conditions can check the source IP, but with Private Google Access, the source IP is internal, so this is less effective.
- ✓
Enable Private Google Access on the subnet and use VPC Service Controls with a service perimeter that includes the VPC and the Cloud Storage bucket.
Why this is correct
VPC Service Controls provide a security perimeter around Google APIs, restricting access from unauthorized networks.
- ✗
Configure a firewall rule that allows egress traffic to the Cloud Storage API only from the instances' subnet.
Why it's wrong here
Firewall rules control network traffic but do not enforce access control on the API itself.
- ✗
Create an IAM condition that restricts access based on the instance's internal IP address range.
Why it's wrong here
Internal IPs can be spoofed or changed; IAM conditions are not the strongest mechanism for network-level restrictions.
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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.