- A
Set up VPC peering between the VPCs in each region.
Why wrong: VPC peering is used to connect two separate VPCs. Since the scenario describes a single VPC with subnets in two regions, peering is not needed.
- B
Set up Cloud VPN or Dedicated Interconnect between the two VPCs.
Why wrong: Cloud VPN or Dedicated Interconnect connects separate VPCs or on-premises networks. Within a single VPC, regional subnets already communicate privately without this.
- C
Create firewall rules allowing all traffic from the other region's subnet CIDR.
Correct. Firewall rules are required to allow traffic between instances. By default, firewall rules may restrict traffic, so rules allowing the desired communication must be created.
- D
Configure instances to use external IP addresses for cross-region communication.
Why wrong: Using external IPs would route traffic over the public internet, violating the requirement to communicate via internal IPs without traversing the internet.
- E
Use a shared VPC to connect both regions.
Why wrong: Shared VPC allows sharing subnets across projects, not connecting regions within the same VPC. It does not affect cross-region communication within a single VPC.
Cross-Region VPC Peering for Private IP Connectivity
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. A key principle to apply: global VPC. 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 VPC with multiple subnets across two regions for high availability. They want to ensure that instances in different regions can communicate using internal IP addresses without traversing the public internet. Which TWO actions should they take? (Choose two.)
Quick Answer
The answer is to set up Cloud VPN or Dedicated Interconnect between the two VPCs, as these services establish encrypted or dedicated private paths that enable cross-region private IP communication using VPC peering principles. This is correct because VPC peering itself is a non-transitive, single-region connection in Google Cloud, so for cross-region private IP connectivity without traversing the public internet, you must use Cloud VPN (with dynamic routing) or Dedicated Interconnect to bridge the VPCs across regions, allowing internal IP addresses to route directly over Google’s global network backbone. On the Google Professional Cloud Network Engineer exam, this tests your understanding of VPC peering limitations versus hybrid connectivity options—a common trap is assuming VPC peering works across regions natively, but it does not in GCP; instead, remember that peering is regional and non-transitive. A helpful memory tip: “Peering is regional, VPN is global—bridge regions with a tunnel or a cable.”
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
Create firewall rules allowing all traffic from the other region's subnet CIDR.
In Google Cloud, a VPC is a global resource. Subnets are regional, but they all belong to the same VPC. Instances in different regions within the same VPC can communicate using internal IP addresses automatically over Google's global network, without needing VPC peering, VPN, or Dedicated Interconnect. The only requirement is that firewall rules permit the traffic. Therefore, the necessary action is to create firewall rules (Option C). Options A and B are for connecting separate VPCs, which is not the scenario here. Options D and E are incorrect because using external IPs would traverse the internet, and Shared VPC is for sharing subnets across projects, not for connecting regions.
Key principle: Global VPC
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Set up VPC peering between the VPCs in each region.
Why it's wrong here
VPC peering is used to connect two separate VPCs. Since the scenario describes a single VPC with subnets in two regions, peering is not needed.
- ✗
Set up Cloud VPN or Dedicated Interconnect between the two VPCs.
Why it's wrong here
Cloud VPN or Dedicated Interconnect connects separate VPCs or on-premises networks. Within a single VPC, regional subnets already communicate privately without this.
- ✓
Create firewall rules allowing all traffic from the other region's subnet CIDR.
Why this is correct
Correct. Firewall rules are required to allow traffic between instances. By default, firewall rules may restrict traffic, so rules allowing the desired communication must be created.
Related concept
Global VPC
- ✗
Configure instances to use external IP addresses for cross-region communication.
Why it's wrong here
Using external IPs would route traffic over the public internet, violating the requirement to communicate via internal IPs without traversing the internet.
- ✗
Use a shared VPC to connect both regions.
Why it's wrong here
Shared VPC allows sharing subnets across projects, not connecting regions within the same VPC. It does not affect cross-region communication within a single VPC.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Candidates may assume that cross-region communication requires additional connectivity like VPC peering or VPN, but Google Cloud's global VPC allows instances in different regions to communicate privately by default using internal IPs. The real trap is forgetting that firewall rules must allow the traffic, not that a Layer 3 connection is needed.
Trap categories for this question
Scenario analysis trap
VPC peering is used to connect two separate VPCs. Since the scenario describes a single VPC with subnets in two regions, peering is not needed.
Detailed technical explanation
How to think about this question
VPC peering uses the AWS global infrastructure to route traffic between VPCs without gateways or VPNs, relying on route table entries and security group rules. For cross-region peering, traffic stays on the AWS backbone, avoiding internet latency and exposure. In contrast, Cloud VPN or Dedicated Interconnect (Option B) also provides private connectivity but is typically used for on-premises to VPC connections or when VPC peering is not feasible due to overlapping CIDRs or organizational policies; however, both options are valid for cross-region private communication, making B also correct.
KKey Concepts to Remember
- Global VPC
- Regional Subnets
- Internal IP Communication
- Firewall Rules
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
Global VPC
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.
Visual reference
What to study next
Got this wrong? Here's your next step.
Review global VPC, then practise related PCNE questions on the same topic to reinforce the concept.
- →
Implementing a Virtual Private Cloud — study guide chapter
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Implementing a Virtual Private Cloud practice questions
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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 — Global VPC.
What is the correct answer to this question?
The correct answer is: Create firewall rules allowing all traffic from the other region's subnet CIDR. — In Google Cloud, a VPC is a global resource. Subnets are regional, but they all belong to the same VPC. Instances in different regions within the same VPC can communicate using internal IP addresses automatically over Google's global network, without needing VPC peering, VPN, or Dedicated Interconnect. The only requirement is that firewall rules permit the traffic. Therefore, the necessary action is to create firewall rules (Option C). Options A and B are for connecting separate VPCs, which is not the scenario here. Options D and E are incorrect because using external IPs would traverse the internet, and Shared VPC is for sharing subnets across projects, not for connecting regions.
What should I do if I get this PCNE question wrong?
Review global VPC, then practise related PCNE questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Global VPC
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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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