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AD, DNS, Cisco 2600 serving up DHCP. Reverse PTR records not being removed from DNS.

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  • AD, DNS, Cisco 2600 serving up DHCP. Reverse PTR records not being removed from DNS.

    Hi all, I just took over a network at my new job. There are a few problems I've notcied and like to get resolved. We have two W2K3 dc's, a whole bunch of Cisco 2600 routers. Here is how the network was setup...


    (Internet)-T1--(Cisco 2600)--(W2K3 DC's)
    |
    (Internet)-T1--(Cisco 2600)--(Switches)--(Computers on LAN)

    So, in each buiilding the Cisco 2600 servs up DHCP to the desktops. Once they get their ip, they register that in DNS. When the clients logout/turn off their computers/or the lease expires the computers are susposed to remove that PTR from DNS. They never do. I was looking at our DNS servers and seen many clients still registered in DNS. Here is a example exported from DNS.

    * anyuser.XXXXX.org is the same user, meaning the same user has that many ptr's in dns.

    Name Type Data
    10.10.4.10 Pointer (PTR) anyuser.XXXXX.org.
    10.10.4.18 Pointer (PTR) anyuser.XXXXX.org.
    10.10.4.28 Pointer (PTR) anyuser.XXXXX.org.
    10.10.4.47 Pointer (PTR) anyuser.XXXXX.org.
    10.10.4.55 Pointer (PTR) anyuser.XXXXX.org.
    10.10.4.69 Pointer (PTR) anyuser.XXXXX.org.
    10.10.4.74 Pointer (PTR) anyuser.XXXXX.org.
    10.10.4.86 Pointer (PTR) anyuser.XXXXX.org.
    10.10.4.101 Pointer (PTR) anyuser.XXXXX.org.
    10.10.4.113 Pointer (PTR) anyuser.XXXXX.org.
    10.10.4.220 Pointer (PTR) anyuser.XXXXX.org.

    If this is in the wrong fourm, I'm sorry.

    Thanks in advance, I hope someone can shed light on this issue.

  • #2
    Re: AD, DNS, Cisco 2600 serving up DHCP. Reverse PTR records not being removed from D

    Clients do not remove their DNS records. You need to enable scavenging on the DNS server.

    Comment


    • #3
      Re: AD, DNS, Cisco 2600 serving up DHCP. Reverse PTR records not being removed from D

      Ok. Thanks for the super quick response. When I was poking around I did noticed that feature. I have enabled it on both DNS server. I assume that after 5 days(it was the default int he days box) that all old records will get removed?

      Again thanks for your help.

      Comment


      • #4
        Re: AD, DNS, Cisco 2600 serving up DHCP. Reverse PTR records not being removed from D

        I looked at the event viewer and this event poped up after I manual scavenged the records.

        The DNS server has completed a scavenging cycle but no nodes were visited. Possible causes of this condition include:

        1) No zones are configured for scavenging by this server.
        2) A scavenging cycle was performed within the last 30 minutes.
        3) An error occurred during scavenging.

        The next scavenging cycle is scheduled to run in 0 hours.

        The event data will contain the error code if there was an error during the scavenging cycle.



        I will google this, but if anyone can see a problem that I don't.. please. advise me.

        Comment


        • #5
          Re: AD, DNS, Cisco 2600 serving up DHCP. Reverse PTR records not being removed from D

          Make sure its enabled not only at the Server level but also on each Zone.

          Comment


          • #6
            Re: AD, DNS, Cisco 2600 serving up DHCP. Reverse PTR records not being removed from D

            I have enabled it on both but also each zone/subnet. Would it be wise to set the Aging/Scavenging for all zones to 5 days. Would there be any problem with setting this value to 3 hours? Sorry I'm so green here and asking so many questions, but thanks for your time.

            Comment


            • #7
              Re: AD, DNS, Cisco 2600 serving up DHCP. Reverse PTR records not being removed from D

              Ok, I spoke with the previous admin from my job. He said he had tried enabling scavenging and it did not work. Could my Cisco routers be causing the problem since they are the ones who are serving up DHCP?

              Comment

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