An interesting problem is occurring with two of my Windows 2000 Servers (SP1) and I was wondering if anyone else has experienced this. I have a Windows 2000 Server with IIS running, pointing to an internal DNS for name resolution. This server does not support anonymous access so you must login to IIS with a domain account. When my client box (W2K Pro), who is also pointing to my internal DNS, attempts to connect to this server via http and by fully qualified name (e.g. http://serverX.domain.com, he is presented with the standard prompt (popup authentication window) for userid, password and domain. Upon entering the correct information, the window returns with the password field blank, indicating that the users was not authenticated (for whatever reason). However, if I follow all of the above steps and substitute the fully qualified name for the systems IP Address (e.g. http://xxx.xxx.xxx.xxx, the login is successful with the same userid and password. At this point the log files don't indicate any problems. Of the 7 servers in my domain, this occurs on two of them. These are also the only two AD controllers. Any thoughts?