Which log file contains the username, domain name, and IP address being used for Synchronized User ID?

The correct choice is the access_server.log. This log file is specifically designed to capture user authentication events, including details about the username, domain name, and IP address associated with synchronized user sessions. It plays a crucial role in providing visibility into the authentication process and user activity, which is essential for security monitoring and auditing in a network environment.

When an administrator is troubleshooting or monitoring user access, the access_server.log gives a detailed view of who is accessing the network, from where, and under which credentials. This information is vital for tracking user actions and assessing potential security risks related to unauthorized access or user behavior patterns.

Other log files like user_activity.log, auth.log, and connection.log serve different purposes. While they may contain information about user interactions or authentication attempts, they do not specifically focus on the synchronized user ID details in the same way as access_server.log. Thus, relying on access_server.log for these specific data points ensures accurate and detailed documentation of user access across the firewall.