Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

We have a web site using NTLM and allow domain users. Browsing the site from a client pc works fine, with domain credentials being passed in silently and the user authenticated. However, from a remote session on the server, browsing to http://[serverdomainname] ends up with a domain prompt and eventual 401 error.

Browsing the site on the server via IP is fine, so we think the domain credentials are getting lost in the hop to the DNS.

We need the behavior to work because we have apps that talk to each other via http requests on the same site, and they get 401 errors, even when we have passed in domain credentials.

We has a Microsoft field engineer out here for 2 days, and no matter what we tried, we could never get authenticated from with in an RDP session.

We tried attaching an SPN to the box and still no luck.

share|improve this question
Huh? I'm really wondering how you arrived at that conclusion about a DNS lookup removing credentials. – John Gardeniers Feb 18 '11 at 2:13
Just a SWAG John, and a dubious one. We could browse ok via IP on the box, but got rejected once we tried the old IIS/Browse method. – Kevin Raffay Feb 23 '11 at 6:39
up vote 0 down vote accepted

I bet this is from the loopback check. That causes the extra auth on the local server.

I answered that over here with the steps to disable it.

share|improve this answer
Thanks so much Scott, I'll try that in the AM. We had a MSFT engineer out here for two days and never thought of that. Good to see that others have had that same experience. – Kevin Raffay Feb 23 '11 at 6:37
Hey Kevin. Glad, glad that worked. It's a tricky one because the error doesn't mention anything obvious. – Scott Forsyth - MVP Mar 1 '11 at 22:25

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.