VPC Network Peering: Requirements and Cross-Organization Use
Which TWO of the following are true regarding VPC Network Peering? (Choose TWO.)
Quick Answer
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.”
⚠ Common exam trap
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.
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
✓
The VPCs' subnet IP ranges must not overlap.
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.
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.
- ✗
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.
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Same concept, more angles
1 more way this is tested on PCNE
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.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.