Duplicate Name On Network ?


  • Hope someone can help.  A user was complaining that there machine was going slow.  Switching it on I see the 'duplicate name on network' message at startup.  This machine's name is PC7.  In the event viewer it suggests that the name is conflicting with another machine, which happens to be called PC8.  Both of these machines are on an SBS 2008 domain, and so cannot possibly have the same name surely.? 

    The WINS service is not running on this server so I couldn't delete any spurious records.  I therefore decided to change to computer name.  I logged in as the domain admin on the workstation and changed it, at which point I was prompted for my username and password.  I wouldn't normally expect to see this when logged in as the admin but I put the credentials in anyway.  I then received a message stating that 'multiple connections to the same computer or resource are not allowed' or something very similar.  At a command prompt I typed 'net use' and confirmed that there were no mapped connections. 

    Next I looked in Local Users and Groups at the Administrators group.  There were some unknown names in there (denoted by the sid numbers), one of which must be the domain admin because I couldn't see it listed. 

    This was looking more and more like a DNS issue so I issued an ipconfig /release, ipconfig /renew, and ipconfig /registerdns.  This made no difference to anything.

    The only other thing I can think of is the DHCP server.  Looking in there I can see that PC8 has multiple enties listed, but not with the address that PC7 has allocated.

    Does anyone have any other suggestions as to how I might go about finding out what is wrong.  I look forward to hearing from anyone who might be able to help.

    Alan Moseley
    Thursday, June 16, 2011 9:25 AM

All replies

  • I assume there is no IP address conflicts (i.e. each computer is assigned a different IP)


    In that case, my solution would be to:

    1. Remove PC7 and PC8 from the domain (i.e. on each change computer, changing it from being a member of your.domain to a workgroup).

    2. In Windows SBS Console under Network or via ADUC, removing the client computer accounts for PC7 and PC8

    3. Rejoining the client PC's to the domain by opening web browser and going to http://connect/

    There may be a simpler way but it's 5pm Friday where I am so I'm outta here! And this method should only take 15 minutes.


    Friday, June 17, 2011 5:04 AM
  • Thanks for your reply.  There are definitley no IP conflicts.  As I explained, I tried renaming the computer and ran into difficulties.  I would like to resolve this (which I still have not unfortunately) before I try anything as drastic as removing it from the domain.  Thanks anyway for your thoughts.

    Alan Moseley
    Friday, June 17, 2011 3:00 PM
  • Hi Alan,


    Thanks for posting here.


    I think we should first narrow down the original issue that the warring message 'duplicate name on network' at startup first.

    You mentioned that you have verified this event form log , could you post that full error event record here ? ID and description .


    Actually if you can confirm that PC8 does not hold the duplicate hostname or IP address after the investigation then we should verify and clean the NETBIOS table and DNS cache on PC7 in order to make sure that cache will not cause this issue and then try to see if this issue will persist by rebooting PC7.


    How To Diagnose and Test TCP/IP or NetBIOS Network Connections in Windows 2000




    Tiger Li

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    Saturday, June 18, 2011 11:10 AM
  • Good luck, I would be interested to hear what you did to solve the problem.

    When this happened to me, I had to get it working again ASAP so the user could get on with work, so I didn't have hours/days to research and get into the nitty-gritty. Having said that, removing/rejoining was a satisfactory soltuion for me anyway.

    In our setup, removing a computer from the domain and rejoining it is not drastic -- as far as I recall, after it rejoins you can't tell that it was ever removed.

    Sunday, June 19, 2011 10:11 PM
  • I have run an nbtstat on PC8 (the PC which is supposedly using the name already), and it definitely does not have the name PC7 registered also.  Running nbstat on PC7 tells me that no names are registered at all, not even under the worksgroup category.  Very strange.  I will try removing it from the domain and adding it back in, if I can, next time I am on site there.
    Alan Moseley
    Wednesday, June 22, 2011 3:55 PM