Duplicate Name Exists on the Network when using DNS Alias

When a client computer connects to a Microsoft Windows 2000-based computer or a Microsoft Windows Server 2003-based computer by using an alias name, the client may receive the following error message:

A duplicate name exists on the network.

Although, you're able to access the computer by FQDN or IP address, you're unable to access it by using DNS alias.

This problem can occur when you try to connect to the server by using a CNAME alias that is created in the DNS zone. For example, this problem may occur with a command similar to the following sample command

net view \\alias.domain

where alias is a CNAME record that is created for the server in the domain zone. The server is not "listening" on the alias, and therefore is not accepting connections to that name.

Here's how to fix this on Windows Server 2003 

To resolve this problem in Windows Server 2003, follow these steps:

  1. Create the CNAME record for the file server on the appropriate DNS server, if the CNAME record is not already present.
  2. 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:
    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.
  3. Restart your computer.

You may also have to set the SPN (Service Principal Name) for the Alias Name.
For example, you may have to enter a command that resembles the following commands:

setspn -a host/aliasname targetserver
setspn -a host/ targetserver