The answer is to create a single VPC network with subnets in each region. This works because a VPC is a global resource that inherently provides internal IP routing between all its subnets, regardless of region, using Google’s global network fabric. For the Google Professional Cloud Network Engineer exam, this tests your understanding that VPCs are global by default—a common trap is overcomplicating the solution by proposing VPNs, peering, or Cloud Interconnect when a single VPC already enables inter-region internal IP communication. The simplest way for inter-region internal IP communication in VPC is to avoid adding extra connectivity services; just add subnets. Remember the memory tip: “One VPC to rule all regions”—if your instances need to talk privately across regions, keep them in the same VPC.
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. 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 network engineer needs to design a VPC network for a global application that will have Compute Engine instances in multiple regions. The instances need to communicate with each other using internal IP addresses. What is the simplest way to enable this communication?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a single VPC network with subnets in each region.
A single VPC network is global and can contain subnets in any region. By placing subnets in each required region within the same VPC, instances can communicate using internal IP addresses (RFC 1918) without any additional connectivity services. This is the simplest and most scalable approach because VPCs inherently provide global routing between subnets.
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 Dedicated Interconnect to connect regions.
Why it's wrong here
Dedicated Interconnect is for hybrid connectivity, not inter-region communication.
Create a single VPC network with subnets in each region.
Why this is correct
A global VPC network inherently provides internal connectivity across regions.
Related concept
Read the scenario before looking for a memorised answer.
✗
Create separate VPC networks per region and peer them.
Why it's wrong here
VPC peering adds complexity and is unnecessary for a single VPC.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may overcomplicate the solution by thinking inter-region communication requires explicit connectivity services like VPN or peering, when in fact a single global VPC network provides this natively.
Detailed technical explanation
How to think about this question
Under the hood, a VPC network is a global resource that uses Google's internal Jupiter network fabric to route traffic between subnets in different regions without traversing the public internet. Each subnet is associated with a region, but the VPC's routing tables automatically propagate routes for all subnets, enabling direct internal IP communication. This design leverages Google's global software-defined networking (SDN) to provide low-latency, high-bandwidth connectivity across regions.
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.
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: Create a single VPC network with subnets in each region. — A single VPC network is global and can contain subnets in any region. By placing subnets in each required region within the same VPC, instances can communicate using internal IP addresses (RFC 1918) without any additional connectivity services. This is the simplest and most scalable approach because VPCs inherently provide global routing between subnets.
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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