- A
VPC B must have a route back to VPC A.
Why wrong: Return path is not required for the forward path condition.
- B
VPC peering must be set up with 'export custom routes' enabled from VPC A.
Export of custom routes is required for the peer to see and use them.
- C
The appliance must be in the same region as VPC A.
Why wrong: The appliance can be in any region within VPC A; region does not affect route usage.
- D
The appliance must have a firewall rule allowing traffic from VPC B.
Why wrong: Firewall rules are needed but not specific to the custom route export condition.
- E
VPC A must have a route with destination inside VPC B and next-hop set to the appliance.
This is the custom route directing traffic to the appliance.
Question 781 of 1,000
VPC Peering with Custom Route to Appliance — Required Conditions
This PCNE practice question tests your understanding of implementing a virtual private cloud. 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 has VPC peering between two VPC networks. They want to ensure that traffic from VPC A to VPC B can use a custom route in VPC A that points to a next-hop appliance in VPC A. Which TWO conditions must be met?
Quick Answer
The answer is that VPC A must have a custom route with a destination inside VPC B and a next-hop set to the appliance, and that custom route must be exported to VPC B via the VPC peering connection. This works because Google Cloud’s VPC peering does not automatically share custom routes; you must explicitly export them from the originating VPC, and the route itself must point to an internal next-hop appliance (like a firewall or NAT instance) within VPC A to intercept and process traffic destined for VPC B. On the Google Professional Cloud Network Engineer exam, this scenario tests your understanding of route exchange mechanics and the distinction between dynamic and custom static routes—a common trap is assuming the appliance can be in a different region or that firewall rules alone satisfy the routing condition. Remember the two-part rule: the route must exist in the source VPC, and it must be exported over the peering. Memory tip: “Export the custom, point to the box.”
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
✓
VPC peering must be set up with 'export custom routes' enabled from VPC A.
Option B is required because custom routes must be exported from VPC A to VPC B via peering. This allows VPC B to learn the route and send return traffic back through the same appliance, ensuring bidirectional communication via the appliance. Without exporting custom routes, VPC B would send return traffic directly via the peering connection, bypassing the appliance. Option E is required because VPC A must have a route that specifies the destination inside VPC B and sets the next-hop to the appliance. This route is what directs the traffic from VPC A to VPC B through the appliance. Options A, C, and D are not necessary for the forward path: VPC B does not need a route back (the return path is handled via export), the appliance can be in any region (it just needs connectivity), and a firewall rule on the appliance is needed but is not a condition specific to using the custom route via 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.
- ✗
VPC B must have a route back to VPC A.
Why it's wrong here
Return path is not required for the forward path condition.
- ✓
VPC peering must be set up with 'export custom routes' enabled from VPC A.
Why this is correct
Export of custom routes is required for the peer to see and use them.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The appliance must be in the same region as VPC A.
Why it's wrong here
The appliance can be in any region within VPC A; region does not affect route usage.
- ✗
The appliance must have a firewall rule allowing traffic from VPC B.
Why it's wrong here
Firewall rules are needed but not specific to the custom route export condition.
- ✓
VPC A must have a route with destination inside VPC B and next-hop set to the appliance.
Why this is correct
This is the custom route directing traffic to the appliance.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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 PCNE exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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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: VPC peering must be set up with 'export custom routes' enabled from VPC A. — Option B is required because custom routes must be exported from VPC A to VPC B via peering. This allows VPC B to learn the route and send return traffic back through the same appliance, ensuring bidirectional communication via the appliance. Without exporting custom routes, VPC B would send return traffic directly via the peering connection, bypassing the appliance. Option E is required because VPC A must have a route that specifies the destination inside VPC B and sets the next-hop to the appliance. This route is what directs the traffic from VPC A to VPC B through the appliance. Options A, C, and D are not necessary for the forward path: VPC B does not need a route back (the return path is handled via export), the appliance can be in any region (it just needs connectivity), and a firewall rule on the appliance is needed but is not a condition specific to using the custom route via peering.
What should I do if I get this PCNE question wrong?
Identify which PCNE exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 24, 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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