The answer is to add a static route in the VPC for the pod IP range (10.200.0.0/16) with next hop set to the VPN gateway. This is required because while the VPC already routes traffic destined for the on-premises 10.100.0.0/16 range to the VPN gateway, the GKE pod subnet (10.200.0.0/16) is a secondary IP range that is not automatically advertised over Cloud VPN. Without this static route, the VPC has no forwarding instruction for return traffic or for routing pod-originated packets toward the on-premises network, causing the connectivity to fail despite the Cloud NAT handling outbound internet traffic. On the Google Professional Cloud Security Engineer exam, this scenario tests your understanding of how GKE pod connectivity interacts with hybrid networking—specifically that pod IPs are not part of the VPC’s primary subnet and must be explicitly routed. A common trap is assuming Cloud NAT or the existing on-premises route is sufficient, but the missing piece is the route for the pod range itself. Memory tip: “Pods need their own path—if the route isn’t there, the packet won’t go anywhere.”
PCSE Configuring network security Practice Question
This PCSE practice question tests your understanding of configuring network security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 GKE cluster in a private cluster mode (no public endpoint) in a custom VPC. The cluster nodes are in a subnet that uses a secondary IP range for pods. The company needs the pods to access an on-premises service over a Cloud VPN connection that terminates in a different region. The on-premises service IP range is 10.100.0.0/16. The VPC has a route for 10.100.0.0/16 pointing to the VPN gateway. However, pods cannot reach the on-premises service. The GKE cluster is configured with a Cloud NAT for outbound internet access. The pod IP range is 10.200.0.0/16. Which step is required to allow pod traffic to reach the on-premises network?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a static route in the VPC for the pod IP range (10.200.0.0/16) with next hop set to the VPN gateway.
The VPC has a route for the on-premises range (10.100.0.0/16) pointing to the VPNgateway, but the GKE cluster's pod IP range (10.200.0.0/16) is not part of the VPC's primary or secondary subnet ranges. By default, GKE pods use IP addresses from a secondary IP range that is not automatically advertised over Cloud VPN. Adding a static route in the VPC for 10.200.0.0/16 with next hop set to the VPN gateway ensures that traffic from pods to the on-premises network is forwarded through the VPN tunnel, allowing the on-premises routers to learn the pod subnet and route return traffic back.
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.
✗
Configure Cloud NAT to also translate pod IPs to the node IPs for on-premises traffic.
Why it's wrong here
Incorrect: Cloud NAT is for internet, not for VPN traffic.
✓
Add a static route in the VPC for the pod IP range (10.200.0.0/16) with next hop set to the VPN gateway.
Why this is correct
Correct: this ensures traffic from pods to on-premises is routed via VPN.
Related concept
Read the scenario before looking for a memorised answer.
✗
Disable IP masquerade in the GKE cluster to use pod IPs directly.
Why it's wrong here
Incorrect: IP masquerade helps with source IP but does not solve routing.
✗
Create a firewall rule allowing traffic from the pod IP range to the on-premises IP range.
Why it's wrong here
Incorrect: firewall rules allow but do not route traffic.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that firewall rules or NAT configuration are the primary solution for connectivity issues, when in fact the missing route for the pod IP range to the VPNgateway is the root cause.
Detailed technical explanation
How to think about this question
In GKE private clusters, pods are assigned IPs from a VPC secondary IP range that is not automatically propagated to on-premises networks via BGP or static routes. Cloud VPN requires explicit routes in the VPC routing table for any source ranges that need to traverse the tunnel; without a route for 10.200.0.0/16, packets from pods to 10.100.0.0/16 are dropped because the VPC has no forwarding entry. Additionally, on-premises routers must have a return route for the pod IP range, which is typically added via BGP announcements from the Cloud Router or a static route on the on-premises side.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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.
Configuring network security — This question tests Configuring network security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a static route in the VPC for the pod IP range (10.200.0.0/16) with next hop set to the VPN gateway. — The VPC has a route for the on-premises range (10.100.0.0/16) pointing to the VPN gateway, but the GKE cluster's pod IP range (10.200.0.0/16) is not part of the VPC's primary or secondary subnet ranges. By default, GKE pods use IP addresses from a secondary IP range that is not automatically advertised over Cloud VPN. Adding a static route in the VPC for 10.200.0.0/16 with next hop set to the VPN gateway ensures that traffic from pods to the on-premises network is forwarded through the VPN tunnel, allowing the on-premises routers to learn the pod subnet and route return traffic back.
What should I do if I get this PCSE 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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