Which log file is primarily used for event investigation and documentation in a SaaS environment?

In a Software as a Service (SaaS) environment, the web server log file plays a crucial role in event investigation and documentation. This is because web server logs track all incoming requests, responses, errors, and user interactions with the service, making them invaluable for identifying issues, monitoring performance, and auditing user behavior.

By analyzing web server logs, organizations can gain insights into how the application is being used, detect security incidents such as unauthorized access attempts, and gather data for compliance purposes. These logs provide detailed information about the users' actions, which helps in reconstructing events for forensic analysis if necessary.

Other log files, such as those from DNS servers, virtual machine managers, and API access logs, contribute to overall monitoring and security but do not focus primarily on the web application's interactions in the same comprehensive manner that web server logs do. Therefore, the web server log file is the primary resource for investigating events and documenting activities in a SaaS environment.