We have several SharePoint Intranet and Internet sites running in a multi-farm environment. These several sites are monitored by a real-time application monitoring tool. One of the SharePoint 2010 Internet site keep going down daily for 5 minutes and automatically its up after 5 minutes. We receive notification alert from the monitoring tool whenever this site goes down. The alert received is something like -
The resource http://www.mySharePointSite.com is not available. Internal Server Error
Reason: Resource Down
I explored Event Viewer logs, ULS log files, SQL Server logs but found nothing related to resouce/site unavailability or any critical message that indicates site unavailability.
What could be the possible reason for site automatically becoming unavailable and what is the best approach to reach to the root cause?