The answer is Cloud VPN, because VPC peering inherently cannot support overlapping IP ranges. When two VPCs use identical CIDR blocks, the peering connection fails due to routing conflicts, as Google Cloud’s VPC peering requires unique, non-overlapping subnets to establish direct routes. Cloud VPN resolves this by creating an encrypted tunnel between the VPCs, where you can apply network address translation (NAT) or filtering to translate or isolate the overlapping addresses, enabling communication without breaking the underlying routing tables. On the Google Professional Cloud Network Engineer exam, this question tests your understanding of VPC peering’s strict IP uniqueness requirement versus Cloud VPN’s flexibility with overlapping IPs—a common trap is assuming you can simply adjust routes or use shared VPC, but neither solves the fundamental conflict. Remember the memory tip: “Peering needs unique IPs; VPN can translate the overlap.”
PCNE Implementing hybrid interconnectivity Practice Question
This PCNE practice question tests your understanding of implementing hybrid interconnectivity. 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.
Company A and Company B both have networks in Google Cloud. They want to connect their VPCs using VPC peering, but they have overlapping IP addresses. How can they resolve this?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Cloud VPN to establish connectivity between the VPCs, as VPC peering cannot handle overlapping IPs.
VPC peering does not support overlapping IP ranges. The only option from the list that can handle overlapping IPs is Cloud VPN with network address translation or filtering.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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 establish connectivity between the VPCs, as VPC peering cannot handle overlapping IPs.
Why this is correct
Cloud VPN can be configured with NAT or traffic selectors to handle overlapping IPs.
Configure Private Service Connect to connect the VPCs.
Why it's wrong here
Private Service Connect is for accessing managed services, not VPC-to-VPC connectivity.
✗
Configure VPC peering with custom route exchange to exclude the overlapping subnets.
Why it's wrong here
VPC peering does not allow selective route exchange; all routes are exchanged automatically.
✗
Use Dedicated Interconnect to connect the VPCs through a central router.
Why it's wrong here
Dedicated Interconnect is for on-premises to VPC, not VPC-to-VPC; would still face overlapping issue.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related PCNE subnetting questions on CIDR, address ranges, and subnet selection.
Implementing hybrid interconnectivity — This question tests Implementing hybrid interconnectivity — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Use Cloud VPN to establish connectivity between the VPCs, as VPC peering cannot handle overlapping IPs. — VPC peering does not support overlapping IP ranges. The only option from the list that can handle overlapping IPs is Cloud VPN with network address translation or filtering.
What should I do if I get this PCNE question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related PCNE subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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