- A
Delete the VPC peering connection between the Staging and Production VPCs.
Why wrong: There is no direct peering between Staging and Production; they are only peered to Shared Services.
- B
Set up a Cloud VPN between each spoke VPC and the Shared Services VPC to enable transitive routing.
Why wrong: Cloud VPN is not needed; VPC peering with custom route exchange can achieve the same.
- C
Configure static routes in each spoke VPC with a next hop to the firewall appliance's internal IP for the destination VPC's subnet ranges.
This forces traffic between spokes to go through the firewall.
- D
Remove the default route (0.0.0.0/0) from the spoke VPCs to prevent direct internet access.
Why wrong: The default route is needed for internet access via Cloud NAT; it does not affect inter-VPC traffic.
- E
Enable the export of custom routes from the Shared Services VPC to the peered VPCs.
This propagates the static routes pointing to the firewall to the spoke VPCs.
PCNE Implementing network security Practice Question
This PCNE practice question tests your understanding of implementing network security. 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 is designing a secure multi-VPC architecture in Google Cloud. They have three VPCs: Production, Staging, and Shared Services. The Shared Services VPC hosts a Cloud NAT for outbound internet access and a set of managed instance groups. The Production and Staging VPCs are peered to the Shared Services VPC. The company wants to ensure that: (1) instances in Staging cannot initiate connections to instances in Production, (2) instances in Production cannot initiate connections to instances in Staging, (3) all VPCs can communicate with Shared Services, and (4) traffic between VPCs must be inspected by a firewall appliance in Shared Services. Which TWO actions should the company take?
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
Configure static routes in each spoke VPC with a next hop to the firewall appliance's internal IP for the destination VPC's subnet ranges.
Option C is correct because configuring static routes in each spoke VPC with a next hop to the firewall appliance's internal IP ensures that traffic between Production and Staging is forced through the firewall in Shared Services for inspection. This satisfies the requirement that all inter-VPC traffic must be inspected, as VPC peering alone does not support transitive routing or traffic inspection.
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.
- ✗
Delete the VPC peering connection between the Staging and Production VPCs.
Why it's wrong here
There is no direct peering between Staging and Production; they are only peered to Shared Services.
- ✗
Set up a Cloud VPN between each spoke VPC and the Shared Services VPC to enable transitive routing.
Why it's wrong here
Cloud VPN is not needed; VPC peering with custom route exchange can achieve the same.
- ✓
Configure static routes in each spoke VPC with a next hop to the firewall appliance's internal IP for the destination VPC's subnet ranges.
Why this is correct
This forces traffic between spokes to go through the firewall.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Remove the default route (0.0.0.0/0) from the spoke VPCs to prevent direct internet access.
Why it's wrong here
The default route is needed for internet access via Cloud NAT; it does not affect inter-VPC traffic.
- ✓
Enable the export of custom routes from the Shared Services VPC to the peered VPCs.
Why this is correct
This propagates the static routes pointing to the firewall to the spoke VPCs.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume VPC peering provides transitive routing automatically, but Google Cloud explicitly does not support transitive peering, requiring manual route configuration to direct traffic through a central inspection appliance.
Detailed technical explanation
How to think about this question
VPC peering in Google Cloud does not support transitive routing, meaning that if Production and Staging are both peered to Shared Services, they cannot communicate with each other through Shared Services unless explicit routes are configured. By adding static routes in each spoke VPC with a next hop to the firewall appliance's internal IP (e.g., 10.0.0.2), traffic is forced through the firewall, which can inspect and enforce security policies. This approach leverages the fact that VPC peering allows custom route exchange when route export is enabled, enabling the firewall to act as a central inspection point.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this PCNE question test?
Implementing network security — This question tests Implementing network security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Configure static routes in each spoke VPC with a next hop to the firewall appliance's internal IP for the destination VPC's subnet ranges. — Option C is correct because configuring static routes in each spoke VPC with a next hop to the firewall appliance's internal IP ensures that traffic between Production and Staging is forced through the firewall in Shared Services for inspection. This satisfies the requirement that all inter-VPC traffic must be inspected, as VPC peering alone does not support transitive routing or traffic inspection.
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 11, 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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