Google Professional Cloud Network Engineer Question 726
Select 3Google Cloud PlatformYou are troubleshooting connectivity issues between two Compute Engine instances located in different VPCs connected via a VPC Network Peering. The instances are unable to communicate with each other. You have verified that the VPC Network Peering is established. What should you check next to resolve the issue?
- A
Verify that the firewall rules in both VPCs allow traffic between the two instances.
- B
Ensure that the VPC Network Peering has been configured for bidirectional routing between the VPCs.
- C
Check if subnet IP ranges in the two VPCs overlap, which can block communication.
- D
Verify that the instances have external IP addresses assigned for cross-VPC communication.
- E
Confirm that the route tables in both VPCs have routes for the peered VPC's subnet IP ranges.
Show answer and explanation
Correct answers: A, C, E
Explanation
When troubleshooting connectivity issues in a VPC Network Peering setup, you should first verify that firewall rules permit traffic, as restrictive rules can block communication. Overlapping subnet ranges can cause routing conflicts, so checking for overlap is critical. Additionally, route tables must have the correct routes for the peered VPC's subnet ranges to ensure traffic is correctly directed. External IPs and bidirectional routing do not apply in this scenario, as peered VPCs leverage internal IPs and automatic bidirectional routing.
- A. Correct.
Firewall rules in both VPCs must explicitly allow traffic between the instances. If the rules are too restrictive, communication will fail.
- B. Incorrect.
VPC Network Peering does not require manual configuration for bidirectional routing; it is automatically handled when the peering connection is established.
- C. Correct.
Overlapping subnet IP ranges between peered VPCs can lead to routing conflicts and prevent communication between instances.
- D. Incorrect.
Instances do not need external IP addresses for communication across peered VPCs; internal IPs are sufficient when the peering is properly set up.
- E. Correct.
Route tables must include routes to the subnet IP ranges of the peered VPC for traffic to flow correctly. Missing or incorrect routes can block communication.