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I have a Windows Server 2003 system on which passwordless access to local UNC paths is possible using the server's unqualified hostname or its IP address, but not via its FQDN -- even when the hosts file is used to map that FQDN directly to

That is:

  • \\\ - passwordless
  • \\myhost\ - passwordless
  • \\\ - brings up an authentication dialog

Unfortunately, I have a local application trying to resolve UNC paths including the host's FQDN.

I've tried resolving to in both hosts and lmhosts, and calling ping at the command prompt gives the appearance that this resolution has taken effect; even so, attempting to open \\\ from Windows Explorer brings up a password prompt, while \\\ does not.

The system is using an OpenDirectory server (Apple's Kerberos+LDAP directory service) for authentication.

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up vote 2 down vote accepted

KB#926642 describes a solution to this, which worked for me:

Add a multi-string value to the registry under the name HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0\BackConnectionHostNames including the hostname(s) or alias(es) which aren't working.

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Try putting in the IE Trusted Sites (or

You may also need to ensure that IE Trusted Sites is configured to use automatic logon with current user name and password.

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Is the IE trusted site list used for Windows File Sharing, as opposed to web browsing? – Charles Duffy May 7 '10 at 3:14
Absolutely. Check out the lower right corner of your Windows Explorer window. It usually lists the applicable IE zone. – Greg Askew May 8 '10 at 18:42

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