The answer is to advertise the pod IP ranges over the Cloud Router BGP session to the on-premises router. This is correct because VPC-native clusters assign pods alias IPs directly from the VPC subnet’s secondary CIDR ranges, making them first-class VPC addresses. For on-premises traffic to return to those pods through the Cloud VPN tunnel, the on-premises router must have a route to those specific pod CIDRs, which is achieved by advertising them via BGP over Cloud Router. On the Google Professional Cloud Network Engineer exam, this scenario tests your understanding of how VPC-native pod routing differs from non-VPC clusters, where pods are hidden behind node IPs. A common trap is assuming that simply enabling the VPN tunnel or using default VPC routes is enough—without BGP advertisement, the on-premises network has no way to learn the pod subnets. Memory tip: think of pod IPs as “hidden guests” that need a formal BGP introduction to the on-premises router before they can receive replies.
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 runs a Kubernetes cluster on GKE with a VPC-native cluster (alias IP ranges). They have pods that need to communicate with on-premises services via a Cloud VPN tunnel. Which networking configuration is required to enable pod-to-on-premises communication?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Advertise the pod IP ranges over the Cloud Router BGP session to the on-premises router.
Option B is correct because VPC-native clusters assign alias IP ranges to pods directly from the VPC subnet's secondary CIDR ranges. To enable on-premises routing to these pods, the pod IP ranges must be advertised over the Cloud Router BGP session to the on-premises router. This ensures the on-premises network learns the routes to the pod CIDRs and can forward traffic back through the Cloud VPN tunnel.
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.
✗
Enable VPC Flow Logs for the subnets to allow traffic to be routed.
Why it's wrong here
Flow logs are for monitoring, not routing.
✓
Advertise the pod IP ranges over the Cloud Router BGP session to the on-premises router.
Why this is correct
BGP advertising ensures on-premises knows how to route back to pods.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure a firewall rule allowing traffic from pod CIDR to on-premises subnets.
Why it's wrong here
Firewall rules control access but do not enable routing; routes are also needed.
✗
Create a VPC peering connection between the VPC and the on-premises network.
Why it's wrong here
VPC peering is for GCP VPCs, not on-premises.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse firewall rules with routing, assuming that allowing traffic in a firewall rule is sufficient for connectivity, when in fact the on-premises router must have a route to the pod CIDRs via BGP advertisement for bidirectional communication.
Detailed technical explanation
How to think about this question
When using a VPC-native cluster, each node gets a /24 alias range from the pod secondary CIDR, and pods receive IPs from these ranges. Cloud Router uses Border Gateway Protocol (BGP) to advertise custom IP ranges, including pod CIDRs, to the on-premises router. Without these advertisements, the on-premises router will drop return traffic because it lacks a route to the pod IPs, even if the pod can initiate outbound traffic through the VPN tunnel.
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: Advertise the pod IP ranges over the Cloud Router BGP session to the on-premises router. — Option B is correct because VPC-native clusters assign alias IP ranges to pods directly from the VPC subnet's secondary CIDR ranges. To enable on-premises routing to these pods, the pod IP ranges must be advertised over the Cloud Router BGP session to the on-premises router. This ensures the on-premises network learns the routes to the pod CIDRs and can forward traffic back through the Cloud VPN tunnel.
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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