Check your availability report on IIS Server
Below are the information that you can get from IIS Server to see your server availability. Health of the IIS Server depends upon the health of the websites. Health of the Website depends upon attributes that are mentioned below:
Bytes Transferred : Bytes Sent Per Second, Bytes Received per Second, Bytes Total Per Second
Next on http://dev.jouledoc.com/2008/08/check-your-availability-report-on-iis-server/