- A
Use the private DNS zone for googleapis.com with the restricted.googleapis.com IP addresses
Why wrong: This is needed for VPC Service Controls but not for basic Private Google Access; the default DNS suffices.
- B
Configure a firewall rule allowing egress to 0.0.0.0/0
Why wrong: Default egress rules allow outbound traffic; no additional firewall rules are needed for Private Google Access.
- C
Ensure the instances have a service account with permissions to access Cloud Storage
IAM permissions are required to access Cloud Storage; Private Google Access only provides connectivity.
- D
Create a Cloud NAT gateway in us-central1
Why wrong: Cloud NAT provides internet access via public IPs; Private Google Access is the proper solution for private API access.
- E
Enable Private Google Access on the subnet in us-central1
This allows instances without external IPs to reach Google APIs via Google's internal network.
PCNE Implementing VPC Instances Practice Question
This PCNE practice question tests your understanding of implementing vpc instances. 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 has a VPC with subnets in us-central1 and europe-west1. They need to allow Compute Engine instances in us-central1 (without external IPs) to access Google Cloud Storage buckets in the US multi-region. They also need to ensure the traffic does not traverse the public internet. Which TWO configurations are required? (Choose TWO.)
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
Ensure the instances have a service account with permissions to access Cloud Storage
Private Google Access allows instances without external IPs to reach Google APIs. It must be enabled on the subnet. Additionally, the DNS name for Google APIs must resolve to the private IP ranges (199.36.153.4/30 for restricted.googleapis.com) or use the default private Google access IPs. For Cloud Storage, the restricted.googleapis.com VIP is used for Private Google Access if the project is in a VPC Service Controls perimeter; otherwise, the default private Google access IPs work. However, to ensure traffic does not go over the public internet, Private Google Access is sufficient as Google's internal network is used. The second required configuration is to enable Private Google Access on the subnet. No additional DNS changes are needed if using the default DNS (the private Google access IPs are returned automatically).
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.
- ✗
Use the private DNS zone for googleapis.com with the restricted.googleapis.com IP addresses
Why it's wrong here
This is needed for VPC Service Controls but not for basic Private Google Access; the default DNS suffices.
- ✗
Configure a firewall rule allowing egress to 0.0.0.0/0
Why it's wrong here
Default egress rules allow outbound traffic; no additional firewall rules are needed for Private Google Access.
- ✓
Ensure the instances have a service account with permissions to access Cloud Storage
Why this is correct
IAM permissions are required to access Cloud Storage; Private Google Access only provides connectivity.
Related concept
CIDR notation defines the prefix length.
- ✗
Create a Cloud NAT gateway in us-central1
- ✓
Enable Private Google Access on the subnet in us-central1
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 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.
Visual reference
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 PCNE subnetting questions on CIDR, address ranges, and subnet selection.
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Implementing VPC Instances — study guide chapter
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FAQ
Questions learners often ask
What does this PCNE question test?
Implementing VPC Instances — This question tests Implementing VPC Instances — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Ensure the instances have a service account with permissions to access Cloud Storage — Private Google Access allows instances without external IPs to reach Google APIs. It must be enabled on the subnet. Additionally, the DNS name for Google APIs must resolve to the private IP ranges (199.36.153.4/30 for restricted.googleapis.com) or use the default private Google access IPs. For Cloud Storage, the restricted.googleapis.com VIP is used for Private Google Access if the project is in a VPC Service Controls perimeter; otherwise, the default private Google access IPs work. However, to ensure traffic does not go over the public internet, Private Google Access is sufficient as Google's internal network is used. The second required configuration is to enable Private Google Access on the subnet. No additional DNS changes are needed if using the default DNS (the private Google access IPs are returned automatically).
What should I do if I get this PCNE 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 PCNE subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
About these practice questions
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Last reviewed: Jul 4, 2026
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.
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