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  • Wierd DNS issue

    I have checked the dns on all my servers and dont see multiple enteries. Could this be a DHCP lease issue????

    *****
    C:\Windows\System32>ping ServerABC

    Pinging ServerABC.pembina.com [192.168.16.X] with 32 bytes of data:
    Reply from 192.168.16.X: bytes=32 time<1ms TTL=127
    Reply from 192.168.16.X: bytes=32 time<1ms TTL=127
    Reply from 192.168.16.X: bytes=32 time<1ms TTL=127



    ****
    C:\Windows\System32>ping -a 192.168.16.X

    Pinging USERPC1.DOMAIN.com [192.168.16.X] with 32 bytes of data:
    Reply from 192.168.16.X: bytes=32 time<1ms TTL=127
    Reply from 192.168.16.X: bytes=32 time<1ms TTL=127
    Reply from 192.168.16.X: bytes=32 time<1ms TTL=127



    *****

    C:\Windows\System32>nslookup 192.168.16.X
    Server: < SHOWS ONE OF MY INTERNAL DNS SERVER IP>


    Name: USERPC1.DOMAIN.com
    Address: 192.168.16.X

  • #2
    Re: Wierd DNS issue

    The second ping with the '-a' option is using DNS, same as the first ping test, but it's doing a reverse lookup (ip to name), where a normal (forward) DNS lookup is name to ip.

    Check your DNS to see if you've got a reverse lookup zone defined. If so, check for that USERPC1 device, and you'll prob. find that name against the ip address you don't want it to have.

    I'm guessing that you want your server to hold a fixed IP, and you're happy that the forward lookup zone entry in DNS reflects that (the first ping test)? If you do a 'ping userpc1', what address does it resolve to?

    Probably sometime in the past, the userpc1 may very well have had that same IP, either thru manual config or a DHCP issue. Check your DHCP scope range(s) to make sure that fixed address isn't being issued to clients, delete the wrong reverse lookup entry, then at the userpc1 device, verify it has an ip you're happy with and then issue 'ipconfig /registerdns' from a cmd line.
    *RicklesP*
    MSCA (2003/XP), Security+, CCNA

    ** Remember: credit where credit is due, and reputation points as appropriate **

    Comment


    • #3
      Re: Wierd DNS issue

      turns out it was in the reverse DNS.. I have alot of enteries in here that are no longer valid. Shouldnt DNS automatically clean these up?


      Would this have anything to do with any new physicall servers that I plug in getting an ip address and name of a server that I already have configured?

      Thanks for your HELP RicklesP
      Last edited by ldev; 11th April 2012, 20:30.

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      • #4
        Re: Wierd DNS issue

        Originally posted by ldev View Post
        turns out it was in the reverse DNS.. I have alot of enteries in here that are no longer valid. Shouldnt DNS automatically clean these up?


        Would this have anything to do with any new physicall servers that I plug in getting an ip address and name of a server that I already have configured?

        Thanks for your HELP RicklesP
        You need to enable scavenging to clear old stale DNS entires.

        http://technet.microsoft.com/en-us/l...(v=ws.10).aspx

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        • #5
          Re: Wierd DNS issue

          Reverse lookup zones aren't handled quite the same as forwards. Have a good look at the properties of your DNS server, and change the behavior for updates as you need for your environment. Don't have it in front of me, but if memory servers, there's an option for automatic reverse updates as well as forward.

          If it's an issue, you could try removing the reverse zone entirely. It's not activated by default when DNS is set up for the domain, so it may not even be needed any more. If removing it breaks something, you can always re-create it. The good thing is that the re-creation will build a new index from the existing forward lookup zone, so all records will be current.

          If nothing breaks after removing the reverse zone, the only thing you'll have lost is a source of frustration.

          Pls remember to add reputation points!
          *RicklesP*
          MSCA (2003/XP), Security+, CCNA

          ** Remember: credit where credit is due, and reputation points as appropriate **

          Comment


          • #6
            Re: Wierd DNS issue

            You do realise that you can set scavenging/aging on a per zone basis or a per server basis???



            To set aging and scavenging properties for the DNS server

            1. Log on to the computer that is running the DNS Server service with an account that is a member of the local Administrators group.


            2. In the DNS console tree, right-click the applicable DNS server, and then click Set Aging/Scavenging for all zones.


            3. Select the Scavenge stale resource records check box.


            4. Modify other aging and scavenging properties as needed.



            To set aging and scavenging properties for a zone

            1. Log on to the computer that is running the DNS Server service with an account that is a member of the local Administrators group.


            2. In the DNS console tree, right-click the applicable zone, then click Properties.


            3. On the General tab, click Aging, and then select the Scavenge stale resource records check box.


            4. Modify other aging and scavenging properties as needed.

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            • #7
              Re: Wierd DNS issue

              Originally posted by wullieb1 View Post
              You do realise that you can set scavenging/aging on a per zone basis or a per server basis???
              Note that you'll need to enable it at the server and the zone. Not an either/or situation.
              Regards,
              Jeremy

              Network Consultant/Engineer
              Baltimore - Washington area and beyond
              www.gma-cpa.com

              Comment


              • #8
                Re: Wierd DNS issue

                Originally posted by JeremyW View Post
                Note that you'll need to enable it at the server and the zone. Not an either/or situation.
                Thanks for the catch.

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