The answer is to use a Global VPC, which in default mode enables low-latency communication between regions using private IPs natively. This works because a Global VPC spans all Google Cloud regions, allowing subnets in us-east1 and europe-west1 to communicate over Google’s global fiber network without needing VPNs or VPC peering—instances simply use internal IPs within the same VPC, ensuring minimal latency. On the Google Professional Cloud Network Engineer exam, this tests your understanding of VPC network architecture and the distinction between default and auto-mode VPCs; a common trap is assuming you need Cloud VPN or Interconnect for cross-region private IP traffic, but a Global VPC already provides this. Remember the memory tip: “One VPC, all regions—no peering needed.”
PCNE Practice Question: Designing, planning, and prototyping a GCP network
This PCNE practice question tests your understanding of designing, planning, and prototyping a gcp network. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 a VPC with subnets in us-east1 and europe-west1. They need low-latency communication between instances in these regions using private IPs only. Which solution should they use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use a Global VPC (default VPC mode).
A Global VPC (default VPC mode) allows subnets in multiple regions to communicate using private IPs natively, without any additional VPN or peering configuration. This is because a Global VPC spans all regions, and instances within the same VPC can reach each other via internal IPs using Google's global network, providing low-latency communication.
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.
✗
Use Cloud VPN to connect the regions.
Why it's wrong here
Cloud VPN is for on-premises connectivity, not intra-VPC.
✗
Use Cloud Interconnect to connect the regions.
Why it's wrong here
Cloud Interconnect is for on-premises connectivity, not intra-VPC.
✗
Use VPC Network Peering between the two regional subnets.
Why it's wrong here
VPC peering is between separate VPCs, not within a single VPC.
✓
Use a Global VPC (default VPC mode).
Why this is correct
Global VPC provides automatic cross-region routing.
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 confuse VPC Network Peering (which connects separate VPCs) with the native inter-region communication within a single Global VPC, leading them to select option C instead of recognizing that a Global VPC already provides private IP connectivity across regions.
Detailed technical explanation
How to think about this question
Under the hood, a Global VPC uses Google's Andromeda software-defined networking to route traffic between regions using internal IPs, leveraging Google's global fiber backbone for low-latency paths. This eliminates the need for external connectivity or peering, as all subnets are part of the same VPC routing table, with automatic route propagation. In real-world scenarios, this is critical for applications like multi-region databases or microservices that require consistent private IP communication without traversing the public internet.
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 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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Designing, planning, and prototyping a GCP network — This question tests Designing, planning, and prototyping a GCP network — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use a Global VPC (default VPC mode). — A Global VPC (default VPC mode) allows subnets in multiple regions to communicate using private IPs natively, without any additional VPN or peering configuration. This is because a Global VPC spans all regions, and instances within the same VPC can reach each other via internal IPs using Google's global network, providing low-latency communication.
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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Question Discussion
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