You plan to move a third project into an existing VPC Service Controls perimeter but need to validate the impact before enforcing the change. What should you do?

The correct approach is to modify the existing VPC Service Controls policy to include the new project in dry run mode. Dry run mode allows you to simulate the enforcement of the perimeter policy without actually blocking any requests. This generates logs in Cloud Logging that show which requests would have been blocked, enabling you to identify and address any potential violations or unintended impacts before fully enforcing the policy. Enabling Firewall Rules Logging or VPC Flow Logs would provide network traffic insights but wouldn't specifically validate the impact of a VPC Service Controls perimeter. Monitoring Resource Manager audit logs would show administrative actions but not the service access enforcement of VPC Service Controls.