none
DHCP applying one IP address to two DNS names RRS feed

  • Question

  • Hello,

    We have a problem occurring on our LAN with one IP being assigned to multiple computer names in DHCP.  The problem is that one computer may be a valid name, but the other computer does not exist.  Meaning that it has been decommissioned from the system and powered off. So for example if I ping computer1.mydomain.com and it returns echo replies for 192.168.2.1, then I could ping computer2.mydomain.com and it returns echo replies for the same ip address but "computer2" does not physically exist.  I have verified that we do not have any rogue dhcp servers on the network.  We do not have dhcp setup on any switches or other layered devices.  I have also verified that there are no DNS A records assoiciated with "computer2" on the system.   Something appears to be identifying a decommissioned computer name then routing the traffic to a valid computer on the network.  Any help that anyone can provide would be greatly appreciated.  Thanks 

    Sincerely,

    Nick A.

    Monday, February 15, 2016 8:51 PM

Answers

All replies

  • try to run ipconfig /displaydns record get the out put . also check your host file on the computer.

    Darshana Jayathilake

    Tuesday, February 16, 2016 1:05 AM
  • Hi Nick,

     

    1. Please check the client’s cache and Hosts file,make sure there is no record for computer2.

     

       2.Do you have WINS server on your network?If you do,please check the WINS record.If not,go to next step.

     

       3.Please check the client’s Netbios cache and LMhosts file.Or you could disable NetBios over TCP/Ip .

     

     

      Best Regards,

    Cartman

    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.

    Tuesday, February 16, 2016 6:08 AM
  • Probably stale DNS records are causing this issue, delete them from DNS.

    Regards, MC Manikandan

    Tuesday, February 16, 2016 8:13 AM
  • Well here are just a few things:

    1. On our network we are not using the lmhosts file on clients.

    2. As stated above, there are no stale DNS records that exist on the Domain controller for computer2.mydomain.com (after checking multiple controllers.)

    3. This is problem is repeatable on multiple computers.

    4. There is no record showing up in WINS on the domain controller.

    5. Unable to find a rogue DHCP server that could be distributing incorrect IPs.

    Nick A.

    Tuesday, February 16, 2016 5:03 PM
  • The DHCP console will do a lookup to find the computer name to display. Somewhere on your network there is a name record for computer2 that points to the IP of computer1. You need to track this down and remove it.

    You cannot have two machines with the same IP on the network, they will flash up with IP conflict warnings so computer2 definately does not exist, you just need to find the record of where "computer2" is coming from and remove it.

    You can try from one of the client's, nslookup computer2.mydomain.com. If you get an IP then it must be DNS name, either from your DNS server or a local hosts file. On that client try "ping computer2." If you get a result back that claims to ping from "computer2.mydomain.com" then it cannot resolve by NetBIOS and it must be a DNS name somewhere. If it returns "computer2" then you check wins or lmhosts.

    Tuesday, February 16, 2016 5:20 PM
  • Try to clear the cache from all DNS servers as well as local machine and check.

    Regards, MC Manikandan

    Tuesday, February 16, 2016 6:28 PM
  • Hi Nick,

    Please disable NetBIOS over TCP/IP and try again.

       Best Regards,

    Cartman

    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.



    Wednesday, February 17, 2016 1:21 AM
  • Have you verified any alias record created in DNS for computer1?
    Wednesday, February 17, 2016 1:31 AM
  • Hi Guys,

    Those steps have been taken and the issue is not resolved...  Question:

    If the computer name still resides in Active Directory after the computer has been removed from the network, could that cause the problem?  Computer2.mydomain.com is still in AD.  The interesting part to this is there are other computers in there that have been pulled from the network that are still in AD that are not redirecting to other clients.

    Nick

    Wednesday, February 17, 2016 6:12 PM
  • Hi Ncik,

    Sorry for delay.Here is the similar issue for your reference:

    https://social.technet.microsoft.com/Forums/windowsserver/en-US/9e509069-01da-4710-a76d-547a410c0c5d/computer-is-pinging-when-i-nslookup-by-hostname-it-is-missing-when-i-rdp-using-hostname-it?forum=winserveripamdhcpdns

    Best Regards,

    Cartman

    Please remember to mark the replies as answers if they help and unmark them if they provide no help. If you have feedback for TechNet Support, contact tnmff@microsoft.com.

    Tuesday, March 1, 2016 8:11 AM