Friday, December 30, 2011

Error 401.1 "Unauthorized: Access is denied due to invalid credentials"

Have developed a ASP.NET application, in which it will call a web service from another web application but within the same IIS server. Everything is fine until putting those into production server.

The web service requires Windows authentication.  Error 401.1 "Unauthorized: Access is denied due to invalid credentials" occur even we pass the correct user name, password.  We ensure the account is not locked.

After Googling, we found that it happens on Windows 2003 Server SP1, IIS6 with integrated authentication enabled.

http://support.microsoft.com/kb/896861

Above KB describe the solution about the loopback issue, I am not repeating there.  The most important thing is it happens to some host name only, not all.

After we do some testing, we find that if the host name is CNAME in our DNS, it works.  But if we set to A (IP address), then no luck.

Example:
name1.mydomain.com -> WEBSERVER01.LOCAL (CNAME)
name2.mydomain.com -> 192.168.1.2 (A)

No problem for name1.mydomain.com, but same problem withe above KB for name2.mydomain.com


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