- A
Assign a public IP to the VMs in both VPCs.
Why wrong: VPC peering uses private IPs; public IPs are not required for peering communication.
- B
Ensure the VPCs have non-overlapping subnet IP address ranges.
Overlapping ranges cause routing conflicts and are not allowed in VPC peering.
- C
Create a peering connection from each project's VPC to the other.
Peering is bidirectional; each side must initiate or accept the connection.
- D
Create a firewall rule allowing all traffic between the VPCs.
Why wrong: Firewall rules are not mandatory to create the peering connection, only to allow specific traffic after the connection is established.
- E
Configure a Cloud Router with BGP sessions.
Why wrong: Cloud Router with BGP is used for Cloud VPN or Dedicated Interconnect, not for VPC peering.
Quick Answer
The answer is that you must create a peering connection from each project’s VPC to the other, making it a bidirectional setup. This is mandatory because VPC peering relies on private IP routing between the two VPCs; if the IP address ranges overlap, the route tables cannot distinguish which VPC a packet belongs to, causing routing conflicts and preventing the connection from being established. On the Google Professional Cloud Network Engineer exam, this question tests your understanding that peering is not a single request but a two-sided agreement, and a common trap is assuming one side can initiate and complete the peering alone. A key prerequisite is ensuring non-overlapping CIDR blocks before initiating the dual creation process. Memory tip: think of VPC peering like a handshake—both hands must reach out, and neither can occupy the same space.
PCNE Implementing a Virtual Private Cloud Practice Question
This PCNE practice question tests your understanding of implementing a virtual private cloud. 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.
A company wants to establish a VPC peering connection between two VPCs in different projects. Which two steps are mandatory to create the peering connection?
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 VPCs have non-overlapping subnet IP address ranges.
Option B is correct because VPC peering relies on private IP routing between the two VPCs. If the IP address ranges overlap, the VPC route tables cannot distinguish which VPC a packet belongs to, causing routing conflicts and preventing the peering connection from being established. Google Cloud requires that the VPCs have non-overlapping subnet CIDR blocks for successful peering.
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.
- ✗
Assign a public IP to the VMs in both VPCs.
Why it's wrong here
VPC peering uses private IPs; public IPs are not required for peering communication.
- ✓
Ensure the VPCs have non-overlapping subnet IP address ranges.
Why this is correct
Overlapping ranges cause routing conflicts and are not allowed in VPC peering.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Create a peering connection from each project's VPC to the other.
Why this is correct
Peering is bidirectional; each side must initiate or accept the connection.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Create a firewall rule allowing all traffic between the VPCs.
Why it's wrong here
Firewall rules are not mandatory to create the peering connection, only to allow specific traffic after the connection is established.
- ✗
Configure a Cloud Router with BGP sessions.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that firewall rules are mandatory for creating a VPC peering connection, but in reality, the peering is a network-layer connectivity setup that can exist without any firewall rules, which are only needed to allow traffic after the peering is active.
Detailed technical explanation
How to think about this question
When you create a VPC peering connection, Google Cloud automatically adds routes for the peered VPC's subnets to each VPC's route table. If the CIDR ranges overlap, the route tables become ambiguous, and the peering request will fail with an error like 'CIDR overlap detected'. In a real-world scenario, overlapping ranges often occur when VPCs are created from default templates or when organizations merge networks without proper IP planning.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
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.
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Implementing a Virtual Private Cloud — study guide chapter
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FAQ
Questions learners often ask
What does this PCNE question test?
Implementing a Virtual Private Cloud — This question tests Implementing a Virtual Private Cloud — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Ensure the VPCs have non-overlapping subnet IP address ranges. — Option B is correct because VPC peering relies on private IP routing between the two VPCs. If the IP address ranges overlap, the VPC route tables cannot distinguish which VPC a packet belongs to, causing routing conflicts and preventing the peering connection from being established. Google Cloud requires that the VPCs have non-overlapping subnet CIDR blocks for successful peering.
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.
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Last reviewed: Jun 30, 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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