Which technology is mentioned as having built-in metrics?

Apache Tomcat is a widely used web application server that serves Java applications and is known for its ability to provide built-in metrics. These metrics typically include information about application performance, request handling, error rates, and resource utilization. These built-in metrics are essential for monitoring and optimizing web applications in real time, making it easier for developers and system administrators to diagnose issues, improve performance, and ensure high availability.

While the other options, such as PostgreSQL, Django, and MySQL, may also offer monitoring capabilities, they do not possess the same level of built-in metrics focused specifically on application performance and server health as found in Apache Tomcat. PostgreSQL and MySQL primarily focus on database management and do not inherently include application-specific metrics. Django is a high-level Python web framework that helps in building web applications but relies on external tools and middleware for monitoring and metrics, rather than providing it out of the box as part of the web server capabilities.