Windows Authentication on Windows 2008 Prompts for Credentials

Question

We're setting up an ASP.NET 4.0 website on Windows Server 2008. The site uses Integrated Windows Authentication for authentication. (It does not use ASP.NET authentication or authorization.)

In IIS, we have only Windows Authentication enabled.

When we browse to the site using localhost as the host header, the site works fine. When we browse to it using the FQDN, the site prompts for username/password but doesn't accept the validly entered credentials.

Some items to note:

• IE does have Integrated Windows Authentication enabled
• The site with FQDN is entered in the Intranet zone in IE
• We've tried adding the site to the Trusted sites to no avail
• We did change the Identity on the AppPool from ApplicationPoolIndentity to Network Service with no success
• We verified that IUSR has read and execute access to the directory and files
• We've set NTAuthenticationProviders to both "NTLM" and "Negotiate,NTLM"

What are we missing?

Thanks.

Answer 1

We were informed finally that the server is not on the same domain as we had been led to believe so it couldn't authenticate against Active Directory. (We had been testing with a local account.)