- A
Configure firewall rules to only allow traffic from the on-premises CIDR to the VPC.
Why wrong: Firewall rules only control network traffic, but do not prevent data exfiltration via API calls that appear to come from allowed IPs.
- B
Use Cloud VPN and Private Google Access to allow on-premises access without public IPs.
Why wrong: Private Google Access enables on-premises access, but does not prevent data from being accessed via the internet from other sources.
- C
Configure a VPC Service Controls perimeter and create an access level that includes the on-premises CIDR range.
VPC Service Controls with an access level effectively restricts API access to the allowed CIDR, preventing data exfiltration via the internet.
- D
Use Cloud IAP (Identity-Aware Proxy) to restrict access based on identity and context.
Why wrong: IAP provides identity-based access, but does not restrict network-level access or prevent egress to the internet.
Google PCA Design for security and compliance Practice Question
This PCA practice question tests your understanding of design for security and compliance. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 designing a VPC Service Controls perimeter to protect data stored in Google Cloud. They need to allow access from their on-premises network via a Cloud VPN tunnel while blocking all internet-based access. What is the most secure and manageable approach?
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
Configure a VPC Service Controls perimeter and create an access level that includes the on-premises CIDR range.
Option C is correct because VPC Service Controls can create a service perimeter that includes the on-premises CIDR via an access level, ensuring data is not exfiltrated to the internet. Option A is wrong because firewall rules do not prevent data exfiltration via API calls. Option B is wrong because IAP is for user identity, not network-level control. Option D is wrong because Private Google Access does not restrict API access from the internet.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure firewall rules to only allow traffic from the on-premises CIDR to the VPC.
- ✗
Use Cloud VPN and Private Google Access to allow on-premises access without public IPs.
Why it's wrong here
Private Google Access enables on-premises access, but does not prevent data from being accessed via the internet from other sources.
- ✓
Configure a VPC Service Controls perimeter and create an access level that includes the on-premises CIDR range.
- ✗
Use Cloud IAP (Identity-Aware Proxy) to restrict access based on identity and context.
Why it's wrong here
IAP provides identity-based access, but does not restrict network-level access or prevent egress to the internet.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related PCA subnetting questions on CIDR, address ranges, and subnet selection.
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Design for security and compliance — study guide chapter
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FAQ
Questions learners often ask
What does this PCA question test?
Design for security and compliance — This question tests Design for security and compliance — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Configure a VPC Service Controls perimeter and create an access level that includes the on-premises CIDR range. — Option C is correct because VPC Service Controls can create a service perimeter that includes the on-premises CIDR via an access level, ensuring data is not exfiltrated to the internet. Option A is wrong because firewall rules do not prevent data exfiltration via API calls. Option B is wrong because IAP is for user identity, not network-level control. Option D is wrong because Private Google Access does not restrict API access from the internet.
What should I do if I get this PCA question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related PCA subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Last reviewed: Jun 24, 2026
This PCA 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 PCA exam.
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