If you follow only the default installation instructions, the PHP Agent treats your entire PHP deployment as a business application with a single tier with a single node. It models your Splunk AppDynamics environment this way even if in reality you have multiple PHP applications running in the same Apache or PHP-FPM pool.

You may have configured your PHP applications as different virtual hosts or FPM pools. With multi-application/single-server (MASS) support, you can monitor several PHP applications running on the same server as separate Splunk AppDynamics entities, represented as different business applications, different tiers or different nodes. Multiple applications running in the same PHP server can have separate metrics, dashboards, health rules, events, and so on. You can monitor them on different controllers, even from different Splunk AppDynamics accounts. You can mix and match the settings to configure the Splunk AppDynamics model that works best for monitoring your entire PHP application environment.

Splunk AppDynamics recommends that you not instrument more than ten applications on a single server.