- A
Move all resources to a single region, such as us-central1, and use a single VPC.
Why wrong: This defeats the purpose of multi-region deployment and may increase latency for users in other regions.
- B
Set up a Cloud VPN tunnel with Cloud Router and use BGP to advertise routes between the two regions.
This provides a dedicated encrypted tunnel and dynamic routing, which can reduce latency by using a more direct path than the public internet.
- C
Create a VPC peering connection between the frontend and backend VPCs.
Why wrong: VPC peering is used to connect separate VPC networks, not to improve routing within the same VPC.
- D
Enable Cloud CDN on the backend load balancer to cache database responses.
Why wrong: Database queries are dynamic and not suitable for caching; Cloud CDN is for static content.
Quick Answer
The correct answer is to set up a Cloud VPN tunnel with Cloud Router and use BGP to advertise routes between the two regions. This solution minimizes inter-region database query latency by forcing traffic between the backend instances in us-west1 and the Cloud SQL database in us-central1 to travel over Google’s global backbone network instead of the public internet, with BGP providing dynamic, optimal routing that avoids congestion and suboptimal paths. On the Google Professional Cloud Network Engineer exam, this scenario tests your understanding of how Cloud VPN with BGP can solve latency issues within a single VPC across regions, often appearing as a trap where candidates mistakenly choose VPC peering or static routes—but those do not offer the dynamic route advertisement needed for cost-effective, low-latency inter-region traffic. Remember the memory tip: “BGP beats the backbone bottleneck”—BGP dynamically selects the best path over Google’s private network, making it the most efficient and budget-friendly choice for cross-region database queries.
PCNE Implementing a Virtual Private Cloud Practice Question
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.
Your company runs a multi-tier web application on Google Cloud. The application consists of frontend instances in a managed instance group (MIG) in us-central1, backend instances in a MIG in us-west1, and a Cloud SQL database in us-central1. The frontend and backend communicate over a VPC network with custom subnet mode (10.0.0.0/16) and use internal IP addresses. Recently, the application experienced intermittent timeouts. You notice that the backend instances in us-west1 have high latency when querying the Cloud SQL database in us-central1. You suspect network congestion or suboptimal routing. You want to minimize latency between the regions for database queries while ensuring the most cost-effective solution. What should you do?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"minimum / minimize"Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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
Set up a Cloud VPN tunnel with Cloud Router and use BGP to advertise routes between the two regions.
Option B is correct because Cloud VPN with Cloud Router and BGP enables dynamic route advertisement between the two regions, allowing traffic between the backend instances in us-west1 and the Cloud SQL database in us-central1 to traverse Google's global network with optimal routing. This minimizes latency by using Google's internal backbone rather than the public internet, and it is cost-effective because Cloud VPN charges only for the tunnel hours and egress traffic, with no per-GB data transfer costs for inter-region traffic within the same VPC.
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.
- ✗
Move all resources to a single region, such as us-central1, and use a single VPC.
Why it's wrong here
This defeats the purpose of multi-region deployment and may increase latency for users in other regions.
- ✓
Set up a Cloud VPN tunnel with Cloud Router and use BGP to advertise routes between the two regions.
Why this is correct
This provides a dedicated encrypted tunnel and dynamic routing, which can reduce latency by using a more direct path than the public internet.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Create a VPC peering connection between the frontend and backend VPCs.
Why it's wrong here
VPC peering is used to connect separate VPC networks, not to improve routing within the same VPC.
- ✗
Enable Cloud CDN on the backend load balancer to cache database responses.
Why it's wrong here
Database queries are dynamic and not suitable for caching; Cloud CDN is for static content.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that VPC peering is needed for inter-region communication within the same VPC, but the trap here is that the frontend and backend are already in the same VPC, so peering is irrelevant, and the real issue is optimizing routing between regions, which Cloud VPN with BGP addresses.
Detailed technical explanation
How to think about this question
Cloud VPN with Cloud Router uses BGP (Border Gateway Protocol) to exchange routes between the on-premises or regional networks and Google Cloud, enabling dynamic route propagation and failover. In this scenario, the backend instances in us-west1 and the Cloud SQL database in us-central1 are in the same VPC but different regions; by default, traffic uses Google's internal backbone, but Cloud VPN with BGP can optimize routing by advertising more specific routes or using custom route advertisements to reduce latency. A real-world scenario where this matters is when an organization has latency-sensitive workloads across regions and needs to ensure traffic takes the most direct path, avoiding potential congestion points in the default routing.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
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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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: Set up a Cloud VPN tunnel with Cloud Router and use BGP to advertise routes between the two regions. — Option B is correct because Cloud VPN with Cloud Router and BGP enables dynamic route advertisement between the two regions, allowing traffic between the backend instances in us-west1 and the Cloud SQL database in us-central1 to traverse Google's global network with optimal routing. This minimizes latency by using Google's internal backbone rather than the public internet, and it is cost-effective because Cloud VPN charges only for the tunnel hours and egress traffic, with no per-GB data transfer costs for inter-region traffic within the same VPC.
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.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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 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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