I am facing this error from sometime. Our application hosts multiple application pools in IIS, but this issue happens only with one/single app pool. All the app pool settings are same across the application pools.
Moreover this failed to respond to a ping is happening only when the app pool is idle. This is not observed when the server is continuously handling incoming requests.
The application pool also does not seem to be hung, as it is able to process the incoming requests as and when requested (verified this by disabling ping mechanism).
Also one more observation is that the issue started to happen only after we enabled the Application initialization (warm up) and enabled the pre-load. Idle time-out is disabled and recycling is set to 3AM every day.
IIS version is greater than 7.5.
I am searching, reading some Microsoft documentation to understand "How WAS ping mechanism works internally and what is the type of ping" to see if something is missing with this one app pool. But all I found is that "WAS checks the app pool health periodically (configured) and restarts in case of failure".
Any suggestions in identifying the problem will be very helpful.
Let me know if you need any additional information.