I have some websites hosted on IIS7.5 windows 2008 R2 sometimes I am notified that sites report an error on connection to DBs and can't connect to DB while sql server is running. Nothing changed on server. If I restart web site still I get that error message. If I recycle the Application pool, web site can connect to DB again.
I used default setting for Application pool and just change it to work under Network service account. I didn't find any useful information on Windows Log or SQL server logs
How can I find the issue and fix it?