This Appendix contains the HTTP and FTP status codes, as listed at
These status codes indicate a provisional response. The client should be prepared to receive one or more 1xx responses before receiving a regular response.
This class of status codes indicates that the server successfully accepted the client request.
200—OK. The client request has succeeded.
The client browser must take more action to fulfill the request. For example, the browser may have to request a different page on the server or repeat the request by using a proxy server.
An error occurs, and the client appears to be at fault. For example, the client may request a page that does not exist, or the client may not provide valid authentication information.
401—Access denied. IIS defines a number of different 401 errors that indicate a more specific cause of the error. These specific error codes are displayed in the browser but are not displayed in the IIS log:
401.2—Logon failed due to server configuration.
401.3—Unauthorized due to ACL on resource.
401.4—Authorization failed by filter.
401.5—Authorization failed by ISAPI/CGI application. ...