Heartbeat Check
From AgileApps Support Wiki
The Heartbeat Check checks to make sure that the platform is still running. It's accomplished by visiting a URL which gets processed by Tomcat. (This lightweight URL gets an gets an immediate response from Tomcat, if it is running.)
If you happen to be logged in, you can visit https://{yourDomain}/networking/rest in your browser. If Tomcat is running, you get a list of REST APIs supported by the platform.
To run the same test without logging in, use a REST client to visit the URL and specify the HEAD method (rather than GET, PUT, or POST). If Tomcat is running, you get an http return code of 200.