Accessing server via different DNS host name

Yesterday night a Windows 2008 server crashed that was protected by Double-Take.  Failed over to the secondary server and the application running on it came up fine.  This morning certain users weren't able to to connect to a share on the secondary server.  Found out that all Windows XP clients couldn't access the share.  Windows 7 users didn't have a problem.

Double-Take makes the standby server take on the identity of the primary server.  One of the actions it performs is to edit the DNS A record of the primary server and change the ip address to that of the secondary server.  SPN (Service Principle Name) was verified, but the Windows XP clients would get an error saying "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".  Connecting by IP wasn't a problem.

To the Windows XP machine, the secondary server is not "listening" on the alias so it is not accepting connections to the name of the primary server.  Windows XP uses SMB 1.0 while Windows 2008 and Windows 7 uses SMB 2.0.  In order for XP to work, a registry entry needs to be applied to the Windows 2008 server.

To resolve this issue on Windows 2003 and Windows 2008:

1. Apply the following registry change to the file server. To do so, follow these 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.
2. Restart your computer.

 http://support.microsoft.com/?id=281308