- A
Auto mode, because it allows overlapping IP ranges with on-premises networks.
Why wrong: Auto mode uses predefined ranges that may overlap; custom mode is better for avoiding overlaps.
- B
Auto mode, because it automatically creates subnets in all regions with predefined IP ranges.
Auto mode creates subnets automatically in each region, which is ideal for minimal manual setup.
- C
Custom mode, because it is the only mode that supports Shared VPC.
Why wrong: Both auto and custom modes support Shared VPC.
- D
Custom mode, because it provides full control over IP ranges.
Why wrong: Custom mode gives control but requires more manual work; auto mode is simpler for a startup needing minimal configuration.
Question 794 of 1,000
PCNE Practice Question: Designing, Planning, and Prototyping a GCP Network
This PCNE practice question tests your understanding of designing, planning, and prototyping a gcp network. 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 startup is setting up their first GCP VPC. They want minimal manual configuration and need subnets in multiple regions. Which VPC creation mode should they use, and why?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"first"Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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
✓
Auto mode, because it automatically creates subnets in all regions with predefined IP ranges.
Auto mode VPCs automatically create a subnet in each region with predefined IP ranges, reducing manual effort. Custom mode requires manual subnet creation.
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.
- ✗
Auto mode, because it allows overlapping IP ranges with on-premises networks.
Why it's wrong here
Auto mode uses predefined ranges that may overlap; custom mode is better for avoiding overlaps.
- ✓
Auto mode, because it automatically creates subnets in all regions with predefined IP ranges.
Why this is correct
Auto mode creates subnets automatically in each region, which is ideal for minimal manual setup.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
CIDR notation defines the prefix length.
- ✗
Custom mode, because it is the only mode that supports Shared VPC.
Why it's wrong here
Both auto and custom modes support Shared VPC.
- ✗
Custom mode, because it provides full control over IP ranges.
Why it's wrong here
Custom mode gives control but requires more manual work; auto mode is simpler for a startup needing minimal configuration.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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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Designing, Planning, and Prototyping a GCP Network — study guide chapter
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FAQ
Questions learners often ask
What does this PCNE question test?
Designing, Planning, and Prototyping a GCP Network — This question tests Designing, Planning, and Prototyping a GCP Network — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Auto mode, because it automatically creates subnets in all regions with predefined IP ranges. — Auto mode VPCs automatically create a subnet in each region with predefined IP ranges, reducing manual effort. Custom mode requires manual subnet creation.
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.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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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