You Were not connected because a duplicate name exists on the network

Problem:

If like me you are trying to add a CNAME alias to an existing computer so you can access it via two different DNS names and you receive the message “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”. Then read on

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;
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanServer\Parameters
  • Create a new DWORD with the following details:
Value name: DisableStrictNameChecking
Data type: REG_DWORD
Radix: Decimal
Value: 1
  • Then reboot the server.

Solution Server for 2008 R2 (and higher):

  • 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;
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
  • Next on 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.

References:

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

http://www.clydesdalesoftware.com/blog/10-02-25/CNAME_rsquo_s_and_SPN_rsquo_s_Access_Denied_Error.aspx

20 thoughts on “You Were not connected because a duplicate name exists on the network”

  1. I have been requested to configure an alias for a server so that users can
    map a drive using the alias instead of the host name.

    I have a 2003 domain in native mode. In the dns server setting up a new
    CNAME record with the name of Testro for a record that already exists in
    DNS (the record is a "file server")

    When I go to cmd prompt on a client computer, I can ping the name and Testro
    successfully resolves the IP address of the file server. If you ping the FQDN of mensagens
    also correctly resolve the IP address of the file server.

    However, if I try to connect to \ \ Testro \ sharename I get the message

    "\ \ Testro \ sharename
    You were not connected because a duplicate name exists on the network. Go to
    system control panel to change the computer name and try again "

    I tried using different values CNAME and whatever I choose
    yet this error. Can someone help me.

    Reply
  2. I was looking for information on **** as I usually face problems in working on *****, so I am happy to find this post very useful for me. These kinds of posts are useful for anyone from beginner to the professional. Thanks for sharing

    Reply
  3. We have 2008R2 Fileserver and failed it over to our DR site.  Long story short all Win7 Systesms worked fine, XP would get the error.  Thanks to your instructions I got the issue resolved!

    Reply
  4. Good day

     

    I Have the same error as above, and it is really strange..it started all of a sudden.

     

    Windows XP machines try to login to Domain and get "Duplicate Name exists on the Network", This is definelty not possible , as the machines have individual ID's, we then login anyway, using the correct credintials, and the profile starts up.

     

    But now I cannot connect to any shared drives, it states "The resource is already in use", sort of the same errors as above..

     

    I have read through the posts above and dont quite understand it.

     

    The DNS / PDC is a Windows 2008 Server.

     

    Thanks Shawn

    Reply
  5. Hi,

    Please take a look at the comment I posted on the 03/27/2010 at 22:01, I believe on 2008 you have to perform an additional step and setup an SPN.

    If you can confirm if that works I will update the post.

    I hope that helps?

    Phil

    Reply
  6. This looks absolutely perfect. All these tinny details are made with lot of background knowledge. I like it a lot. This was a useful post and I think it is rather easy to see from the other comments as well that this post is well written and useful

    Reply
  7. Hy!
    Thanks for your help. We had this problem, with Windows 2k8 R2 server and several XP clients. The reg key and the spn worked like a charm!
    Cheers

    Reply
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