What is the purpose of the _audit index in Splunk?

The _audit index in Splunk is specifically designed to track audit trails. This index captures events related to user access and actions performed within the Splunk environment, such as logins, searches, and configuration changes, thereby providing a comprehensive audit trail of activity. Monitoring user behavior and system activity is crucial for ensuring compliance, security, and operational integrity.

Tracking audit trails helps administrators understand who accessed the system, what actions were taken, and when these actions occurred, which is essential for accountability and troubleshooting potential issues. The information stored in the _audit index can also be used for forensic investigations if security incidents arise.

While monitoring system health and performance are important aspects of managing a Splunk environment, they do not relate specifically to the purpose of the _audit index. Additionally, storing application logs pertains to different indexes that capture operational data from sources other than user actions. Therefore, the option that best describes the purpose of the _audit index is to track audit trails, as it plays a critical role in maintaining security and accountability within the system.