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Client computers getting incorrect DNS addresses RRS feed

  • Question


  • All of my client machines are picking up the incorrect server address when using nslookup. I also get the incorrect DNS Servers when using ipconfig /all
    C:\Users\>nslookup
    Default Server:  UnKnown
    Address:  192.168.3.2
    
    C:\Users\>ipconfig /all
    *(edited for relavent info)*
    Default Gateway . . . . . . . . . : 192.168.3.1
    DHCP Server . . . . . . . . . . . : 192.168.3.1
    DNS Servers . . . . . . . . . . . : 192.168.3.2
    . . . . . . . . . . . . . . . . . : 192.168.2.70
    NetBIOS over Tcpip. . . . . . . . : Enabled
    

    This 192.168.3.2 server in question was a partially setup DC that had the DNS role installed but I didnt believe it was actually being used. It appeared to be in a failed promotion state and I ended up having to do a dcpromo forced removal and metadata cleanup to remove it. I have searched throughout the DNS Management and AD Sites & Services and removed all traces which is the reason NSLOOKUP comes back with Unknown but I cannot find where it is being pulled from. Also, the DHCP and Gateway are running on an old Cisco ASA but it is only using the 192.168.2.70 address for DNS. If I manually configure a computer's primary and secondary DNS then everything is fine but currently all of our client computers are set to auto. The primary DNS should be 192.168.3.40 as it is the PDC with the FSMO role, DNS and other key functions.

    C:\Users\>netsh dhcp show server
    
    6 Servers were found in the directory service:
    Server [SERVER.company.local] Address [192.168.1.2] Ds location: cn=SERVER.company.local
    Server [exch2k7.company.local] Address [192.168.2.3] Ds location: cn=exch2k7.company.local
    Server [server.company.local] Address [192.168.3.40] Ds location: cn=server.company.local
    Server [server-dc2.company.local] Address [192.168.2.70] Ds location: cn=Server-dc2.company.local
    Server [server-dc2.company.local] Address [10.10.10.20] Ds location: cn=Server-dc2.company.local
    Server [server-hyperv.company.local] Address [192.168.1.3] Ds location: cn=server-hyperv.company.local
    

    The only actual functioning DHCP in this list is 192.168.2.70 but it is at our Colo and doesn't have any client machines it is managing. 

    C:\Users\>nltest /dnsgetdc:company.local
    List of DCs in pseudo-random order taking into account SRV priorities and weights:
    
    Non-Site specific:
       server-dc2.company.local  192.168.2.70
       exch2k7.company.local  192.168.2.3  10.10.10.10
       server.company.local  192.168.3.40
    The command completed successfully
    
    Wednesday, January 20, 2016 8:19 PM

Answers

  • Try to release the IP using ipconfig /release then run ipconfig /renew. That will force the IP lease renewal. If all is fine with your DHCP then you should no longer get the wrong DNS IPs. If you still get the wrong ones then there is something wrong with your DHCP.

    This posting is provided AS IS with no warranties or guarantees , and confers no rights.

    Ahmed MALEK

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    Thursday, January 21, 2016 12:15 AM

All replies

  • Well, update your DHCP server to hand out proper DNS servers to the clients, and flush dns on the clients.

     

    Wednesday, January 20, 2016 10:20 PM
  • Try to release the IP using ipconfig /release then run ipconfig /renew. That will force the IP lease renewal. If all is fine with your DHCP then you should no longer get the wrong DNS IPs. If you still get the wrong ones then there is something wrong with your DHCP.

    This posting is provided AS IS with no warranties or guarantees , and confers no rights.

    Ahmed MALEK

    My Website Link

    My Linkedin Profile

    My MVP Profile

    Thursday, January 21, 2016 12:15 AM

  • Hi Daniel,

    >>The only actual functioning DHCP in this list is 192.168.2.70 but it is at our Colo and doesn't have any client machines it is managing. 

    If other DHCP servers are not functioning, you should unauthorize them or uninstall the DHCP roles on them. Then then would not offer IP address to clients.<u1:p></u1:p><o:p></o:p>

    >> All of my clientmachines are picking up the incorrect server address when using nslookup.<u1:p></u1:p><o:p></o:p>

    Client's got DNS server address from DHCP server. And DNS server is configured in scope options on DHCP server. Considering all clients have the same issue, so you should run ipconfig/release, then run ipconfig/renew as Mr X mentioned and check the result.

    Best regards.

    Leo                                                                             


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    Thursday, January 21, 2016 5:13 AM
    Moderator
  • May need to elaborate some.  The DHCP server at 192.168.2.70 functions but being at our Colo it is only handing out addresses to servers which are all setup with static so its rather irrelevant.  The system that is handling the DHCP for clients is our Cisco ASA but it only has 192.168.2.70 configured for the DNS scope.  There was a new 2012 R2 DC server that was being setup that I mistakenly had 192.168.2.70 and 192.168.3.2 in its scope but when we were having problems I demoted it and removed all traces of it (I believe).  I have run ipconfig /flushdns, registerdns, release and renew many many times but its still there.  I don't know if maybe its hiding somewhere in ADSI or what.  I'd be happy if my machines were only showing the 2.70 from the Cisco DHCP.
    Thursday, January 21, 2016 3:51 PM
  • Hi Daniel,

    If you are aware of which device is offering IP address to clients, you should configure the correct DNS server address on the scope. If Cisco ASA, you could ask Cisco support fot help. If you have more than one DHCP server which is available to offer IP address to clients, you may configure DHCP failover.

    Run ipconfig /release, and ipconfig /renew. Then the client would request a new IP address from DHCP server. Ipconfig /flush and /registerdns are not related to the DHCP process.

    To analyze, you may perform a network capture. You could find out which DHCP server is offering accoring to the packets.

    Best Regards,

    Leo


    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.

    Friday, January 22, 2016 2:53 AM
    Moderator