The answer is that Private Google Access must be enabled on the subnet where the instance resides. This configuration is required because VPC Service Controls create a security perimeter around Google Cloud Storage buckets, blocking all external access by default; enabling Private Google Access on the subnet allows the instance to reach Google APIs and services—including the protected bucket—using its internal IP address, bypassing the public internet. On the Google Professional Cloud Security Engineer exam, this scenario tests your understanding of how VPC Service Controls interact with networking, often appearing as a trap where candidates mistakenly think a Cloud NAT or external IP is needed. The key insight is that Private Google Access provides the internal connectivity bridge, while VPC Service Controls enforce the data exfiltration prevention. Remember the mnemonic: “Private Access, Public Bypass”—if you need internal-only API access within a service perimeter, always enable Private Google Access on the subnet.
PCSE Configuring network security Practice Question
This PCSE practice question tests your understanding of configuring network security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 using VPC Service Controls to protect their Google Cloud Storage buckets. They want to allow a specific instance to access a bucket from within a VPC. What networking configuration is required?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Private Google Access must be enabled on the subnet
VPC Service Controls require Private Google Access to be enabled on the subnet so that the instance can access Google APIs using its internal IP address.
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.
✗
The instance must have a public IP
Why it's wrong here
VPC Service Controls are designed to work without public IPs.
✗
A VPC peering connection to Google services
Why it's wrong here
VPC peering is for connecting VPC networks, not for accessing Google APIs privately.
✗
A Cloud NAT gateway
Why it's wrong here
Cloud NAT is for outbound internet access, not for private access to Google APIs.
✓
Private Google Access must be enabled on the subnet
Why this is correct
Private Google Access allows instances with internal IPs to reach Google APIs through Google's private network.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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 PCSE subnetting questions on CIDR, address ranges, and subnet selection.
Configuring network security — This question tests Configuring network security — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Private Google Access must be enabled on the subnet — VPC Service Controls require Private Google Access to be enabled on the subnet so that the instance can access Google APIs using its internal IP address.
What should I do if I get this PCSE 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 PCSE 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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Question Discussion
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