- A
Use an RFC 1918 private IP range (10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16).
Private ranges are required for internal communication.
- B
Use a subnet size of /16 or larger to provide ample IP addresses.
Why wrong: Subnet size is a design choice, not a rule.
- C
Avoid using the same IP range used by other VPCs in the organization.
Unique ranges prevent conflicts.
- D
Ensure the new VPC's CIDR does not overlap with 10.1.0.0/16 or 172.16.0.0/12.
Overlap would cause routing issues.
- E
Allocate public IP addresses for private use to ensure uniqueness.
Why wrong: Public IPs are not needed for private communication.
Question 900 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. 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 planning IP address ranges for a new VPC that will be peered with an existing VPC (10.1.0.0/16) and connected to an on-premises network (172.16.0.0/12). Which three considerations should they follow to avoid IP overlap? (Choose THREE.)
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
✓
Use an RFC 1918 private IP range (10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16).
IP addresses must be unique across connected networks; using RFC 1918 private ranges is standard; avoiding overlapping with on-premises and peered VPC ranges is critical.
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 an RFC 1918 private IP range (10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16).
Why this is correct
Private ranges are required for internal communication.
Related concept
CIDR notation defines the prefix length.
- ✗
Use a subnet size of /16 or larger to provide ample IP addresses.
Why it's wrong here
Subnet size is a design choice, not a rule.
- ✓
Avoid using the same IP range used by other VPCs in the organization.
Why this is correct
Unique ranges prevent conflicts.
Related concept
CIDR notation defines the prefix length.
- ✓
Ensure the new VPC's CIDR does not overlap with 10.1.0.0/16 or 172.16.0.0/12.
Why this is correct
Overlap would cause routing issues.
Related concept
CIDR notation defines the prefix length.
- ✗
Allocate public IP addresses for private use to ensure uniqueness.
Why it's wrong here
Public IPs are not needed for private communication.
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.
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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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: Use an RFC 1918 private IP range (10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16). — IP addresses must be unique across connected networks; using RFC 1918 private ranges is standard; avoiding overlapping with on-premises and peered VPC ranges is critical.
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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