The answer is that VPC Network Peering can be used to connect VPCs in different organizations, and it requires that the subnet IP ranges of the peered VPCs do not overlap. This non-overlap requirement is fundamental because GCP routes traffic based on the destination IP’s longest prefix match against the peered VPC’s subnet CIDR blocks; if ranges overlap, the router cannot determine which VPC should receive the packet, causing routing conflicts and broken connectivity. On the Google Professional Cloud Network Engineer exam, this concept often appears as a distractor where candidates mistakenly think overlapping ranges are allowed or that peering is restricted to the same organization—a common trap. The key is remembering that VPC Network Peering is a global, cross-organizational feature, but it demands unique IP space to function. Memory tip: think “Peering without overlapping—like two neighbors sharing a fence, not the same yard.”
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. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Which TWO of the following are true regarding VPC Network Peering? (Choose TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The VPCs' subnet IP ranges must not overlap.
Option A is correct because VPC Network Peering requires that the subnet IP ranges of the peered VPCs do not overlap. Overlapping ranges would cause routing conflicts and ambiguous destination addresses, as GCP uses the subnet CIDR blocks to determine the next hop for traffic. If two VPCs have overlapping ranges, packets cannot be reliably forwarded to the correct destination, breaking the peering connection.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 VPCs' subnet IP ranges must not overlap.
Why this is correct
Overlapping IP ranges are not allowed in VPC peering.
Related concept
Read the scenario before looking for a memorised answer.
✗
It supports transitive routing across multiple peering connections.
Why it's wrong here
VPC peering does not support transitive routing; each peering is a direct relationship.
✗
It supports exchange of routes with custom dynamic routing.
Why it's wrong here
Custom dynamic routes are not exchanged via peering.
✗
Custom dynamic routes are automatically exchanged.
Why it's wrong here
Only subnet routes are exchanged; custom dynamic routes are not.
✓
It can be used to connect VPCs in different organizations.
Why this is correct
VPC peering can be set up between VPCs in different projects and organizations.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that VPC Network Peering supports transitive routing or dynamic route exchange, leading candidates to select options B or C, when in fact peering is strictly non-transitive and only exchanges subnet and static routes.
Detailed technical explanation
How to think about this question
Under the hood, VPC Network Peering uses a flat routing model where each VPC's subnet routes are imported into the other VPC's routing table as system-generated routes with a priority of 0. Custom dynamic routes (e.g., from Cloud Router BGP sessions) are not exchanged because peering is designed for direct VPC-to-VPC connectivity without transit, and GCP enforces this by not importing dynamic routes. In a real-world scenario, if you need transitive routing, you must use a VPN or a third-party appliance, as peering alone cannot forward traffic beyond the directly peered VPC.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Designing, planning, and prototyping a GCP network — This question tests Designing, planning, and prototyping a GCP network — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The VPCs' subnet IP ranges must not overlap. — Option A is correct because VPC Network Peering requires that the subnet IP ranges of the peered VPCs do not overlap. Overlapping ranges would cause routing conflicts and ambiguous destination addresses, as GCP uses the subnet CIDR blocks to determine the next hop for traffic. If two VPCs have overlapping ranges, packets cannot be reliably forwarded to the correct destination, breaking the peering connection.
What should I do if I get this PCNE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. An organization has two VPC networks in different Google Cloud organizations. They need to allow private IP communication between instances in these VPCs without using public IPs or VPNs. Which solution should they use?
hard
A.Cloud NAT
B.Shared VPC
C.Cloud VPN
✓ D.VPC Network Peering
Why D: VPC Network Peering allows private IP connectivity between two VPC networks across different organizations without requiring public IPs, VPNs, or gateways. It uses the Google Cloud internal infrastructure to route traffic directly between instances, leveraging RFC 1918 addresses and supporting global peering.
Last reviewed: Jun 30, 2026
Question Discussion
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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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