Description of Microsoft Internet Information Services (IIS) 5.0 and 6.0 status codes
Description of Microsoft In...s codes

HTTP status codes in IIS 7.0
When you try to access content on a server that is running Internet Information Services (IIS) 7.0 by using HTTP, IIS 7.0 returns a numeric code that indicates the status of the response. The HTTP status code is recorded in the IIS log. Additionally, the HTTP status code may be displayed in the client browser.

The HTTP status code may indicate whether a request is successful or unsuccessful. The HTTP status code may also reveal the exact reason that a request is unsuccessful.