Where should Zoie check for concurrent session usage in her web application?

In web applications, concurrent session usage typically refers to the ability to track multiple active sessions for the same user or different users at the same time. The web application server logs are the most appropriate place for Zoie to check this information.

Web application server logs provide detailed records of user interactions with the application, including session initiation, activity, and termination. These logs can reveal how many sessions a user has opened, how long those sessions have been active, and whether any limitations on concurrent sessions are being enforced. By analyzing these logs, Zoie can gain insights into user behavior and performance issues, as well as identify potential security risks related to session management.

Other sources, such as network traffic logs, might contain some relevant information about connections to the web application, but they do not usually provide the granularity or specifics regarding session management that the application server logs would. Database logs primarily focus on interactions with the database, while system error logs capture issues related to system operations, rather than user session tracking. Therefore, the web application server logs are the most suitable choice for monitoring and analyzing concurrent session usage.