You are managing an application that runs in Compute Engine. The application uses a custom HTTP server to expose an API that is accessed by other applications through an internal TCP/UDP load…

Packet Mirroring is for deep packet inspection and network forensics, which is a more complex and resource-intensive solution than simply logging IP addresses for access.

Installing the Ops Agent collects logs *from* the instance, but it's not the primary or most efficient way to capture network-level access IPs for a load-balanced service across all connections.

Enabling logging on the firewall rule only logs when a rule is hit or denied, providing less comprehensive flow information compared to VPC Flow Logs, which capture details for all traffic.

Enabling VPC Flow Logs on the subnet will capture metadata about all IP traffic flows, including source and destination IP addresses, that pass through the subnet's network interfaces. This directly fulfills the requirement to log each IP address accessing the API with minimal configuration changes.