title: NTLM Authentication fails ONLY with IE against 2k8 App server behind 2k8 IIS7 Reverse Proxy
body: <p>I'm developing an ASP.NET application for an intranet site that is using Windows/NTLM/WIA/whatever authentication.  The application is hosted on a Windows 2k8 server but is accessed through a Reverse Proxy using IIs7 on another 2k8 machine.</p>
  
  <p>Authentication works fine in FireFox, Chrome and Safari but fails in IE8.  If I circumvent the Proxy and access the application server directly then it works fine so it has something to do with proxy.</p>
  
  <p>There's nothing in the Event Viewer on any of the 3 machines to indicate what might be happening.</p>
  
  <p>If you connect using IE8 it prompts for your credentials instead of automatically passing them, yes I've setup an explicit trust over an above the domain trust, but it still errors out with a 401 error returned from the proxy.</p>
  
  <p>Any ideas where to start troubleshooting this?</p>