Duplicate name , when Mapping a Drive Fix

“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”. Fix for the error.


Solution for Server 2000, 2003, 2008

  • First in DNS create a CNAME record instead of a normal Host(A) record.
  • The next thing to do is to create a new DWORD key in the registry, on the server open regedit and navigate to;

Microsoft Registry

1 HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanServer\Parameters
  • Create a new DWORD with the following detail;




Value name: DisableStrictNameChecking

Data type: REG_DWORD

Radix: Decimal

Value: 1

Then reboot the server.

Solution for 2008 R2,2012 , 2012 R2 (and higher):

Do the Step above for 2000-2008, (but don;’t reboot) then:

On the server create SPN’s for the flat name and the fully qualified name matching your CNAME alias, open up a command prompt and run the below;





setspn -A host/<your_ALIAS_name> <ServerrName>

setspn -A host/<your_ALIAS_name.domain.com> <ServerNname>

Then reboot the server.


2 thoughts on “Duplicate name , when Mapping a Drive Fix

  1. Just for clarification, should these steps be performed on the client machine that you’re adding the mapped drive to, or on the server that you’re targeting with the drive mapping…

    • Hi, The CNAME and the SetSPN commands are done on the server your are trying to map the drive to.
      So you have a server called NEWSERVER and you want the alias OLDSERVER to also be used. So you create a CNAME called OLDSERVER and point it to NEWSERVER.
      Then you log in to the NEWSERVER and use setSPN to setspn -A host/OLDSERVER NEWSERVER
      if you are ever going to use the FQDN of the Server then you need to set a SPN for that as well. e.g. your domain is MYDOMAIN.COM so :setspn -A host/OLDSERVER.MY.DOMAIN.COM NEWSERVER

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