TechTip: Microsoft Windows File Sharing - "You were not connected because a duplicate name exists on the network."

The Problem

Microsoft file sharing and WINS/NetBIOS... can't live with it, can't live without it. One of the seldom encountered, but very obscure problems is accessing file shares on the servers, using CNAME instead of the actual server name in the UNC path. This issue is becoming more and more apparent with many NAS servers being virtualized but needing to keep their name for transparent end-user transition.

It seems the server might not like that fact that is resolving for a name that is different that its own.

Here is the example

FILESERVER.domain.com >>> Resolves to CNAME of SOMECOMPLIANTVMFILESERVERNAME123.domain.com

We can access the share

\\SOMECOMPLIANTVMFILESERVERNAME123\AFolderShare
just fine, but when end users attempt to connect to the server by its pre-migration, user-friendly name \\FILESERVER\AFolderShare (that they are used to and have shortcuts to), they receive the following obscure error message:

System error 52 has occurred.

You were not connected because a duplicate name exists on the network. Go to System in Control Panel to change the computer name and try again.

Looks scary, but it's pretty easy to fix.

The Solution

After some research (and you have to give Microsoft credit for their ever so informative KB), there is a great article that addresses this problem exactly to the point, but that has a very wordy and obscure title: "Connecting to SMB share on a Windows 2000-based computer or a Windows Server 2003-based computer may not work with an alias name" - which can be translated in plain English as "Connecting to a Windows file server share using DNS CNAME".

Unfortunately to fix the problem on both Windows 2000 and Windows 2003 registry modification and server reboot are required, but it does resolve the above issue. Solution for Windows 2003 is pretty straightforward:

To resolve this problem in Windows Server 2003, complete the following steps:
  1. Start Registry Editor (Regedt32.exe).
  2. Locate and click the following key in the registry:
    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanServer\Parameters
  3. On the Edit menu, click Add Value, and then add the following registry value:
    Value name: DisableStrictNameChecking
    Data type: REG_DWORD
    Radix: Decimal
    Value: 1
  4. Quit Registry Editor.
  5. Restart your server.
To resolve the problem on Windows 2000, a custom Hotfix or latest Service Pack is required in addition to the above registry modifications. For more information see the complete article: http://support.microsoft.com/kb/281308

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