Every few hours, the Notification Server will reject NSEs and the agents on client computers will show as disconnected.
The following error appears in the Notification Server (SMP) log files.
Operation 'Direct: Head' failed.
Protocol: HTTPS
Host: [Host FQDN:443]
Path: /altiris/NS/Agent/PostEvent.asp
Connection Id: 4886.10236
Communication profile Id: [GUID of Communication Profile]
Throttling: 0 0 0
Error type: HTTP error
Error code: HTTP status 503: The service is temporarily overloaded (0x8FA101F7)
ITMS 8.x
In IIS, the Application Pool Queue Length Property is set to the default value of 1000.
The following is from the Microsoft document called, ApplicationPool.QueueLength Property. The following is found under the section called "Remarks":
"When the maximum number of requests in the queue has been reached, the service returns an out-of-service message (503: Service Unavailable) to any additional requests to the current application pool."
Please work with Microsoft to Optimizing IIS Performance.