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  • (Reverse) DNS issue

    I'm having a weird (too me at least, it will probably be quite clear to most others ) issue related to DNS.

    If I ping PC1 using: ping PC1 I get an address 192.168.1.245
    If I ping using: ping -a 192.168.1.245 I get the host name of some other PC (not PC1).

    DNS is running on Windows 2003 servers. Since I'm not very friendly with DNS I first checked if server Aging/Scavenging is enabled and it is not. Could this be the issue? Should I enable Aging/Scavenging using the default 7, 7 on all servers? Are there any problems that can come as a result?

    Any help would be great.

  • #2
    Re: (Reverse) DNS issue

    Have you checked in the forward and reverse lookup zones if that hostname-IP pairing exists? If you're concerned about problems that might arise from enabling scavenging, that seems like a good place to start.
    Gareth Howells

    BSc (Hons), MBCS, MCP, MCDST, ICCE

    Any advice is given in good faith and without warranty.

    Please give reputation points if somebody has helped you.

    "For by now I could have stretched out my hand and struck you and your people with a plague that would have wiped you off the Earth." (Exodus 9:15) - I could kill you with my thumb.

    "Everything that lives and moves will be food for you." (Genesis 9:3) - For every animal you don't eat, I'm going to eat three.

    Comment


    • #3
      Re: (Reverse) DNS issue

      gforceindustries: I can find a reverse record of PC2 which matches 192.168.1.245 and a forward record for PC2 that is some strange IP not part of our (current) network configuration.
      I can't find a record for PC1 anywhere.

      BTW there instances in the reverse lookup zone where a single host has a dozen records with different IPs, is that to be expected? Don't see this in the forward zone.

      Comment


      • #4
        Re: (Reverse) DNS issue

        Indeed enable scavenging and aging.
        Marcel
        Technical Consultant
        Netherlands
        http://www.phetios.com
        http://blog.nessus.nl

        MCITP(EA, SA), MCSA/E 2003:Security, CCNA, SNAF, DCUCI, CCSA/E/E+ (R60), VCP4/5, NCDA, NCIE - SAN, NCIE - BR, EMCPE
        "No matter how secure, there is always the human factor."

        "Enjoy life today, tomorrow may never come."
        "If you're going through hell, keep going. ~Winston Churchill"

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        • #5
          Re: (Reverse) DNS issue

          If our DNS is as messed up as it appears is there anything that can go wrong if I enable it (or even if it was in better shape).

          Should I be backing up something (we have DNS running on 3 servers). Where exactly should I enable it?

          Comment


          • #6
            Re: (Reverse) DNS issue

            I don't think your DNS is messed up necessarily, it's just that you've accumulated outdated records because scavenging is disabled, and because clients have been getting allocated different IP addresses from time to time.

            As for backups... do you not already take them?
            Gareth Howells

            BSc (Hons), MBCS, MCP, MCDST, ICCE

            Any advice is given in good faith and without warranty.

            Please give reputation points if somebody has helped you.

            "For by now I could have stretched out my hand and struck you and your people with a plague that would have wiped you off the Earth." (Exodus 9:15) - I could kill you with my thumb.

            "Everything that lives and moves will be food for you." (Genesis 9:3) - For every animal you don't eat, I'm going to eat three.

            Comment


            • #7
              Re: (Reverse) DNS issue

              gforceindustries thank you, all clear.
              A SystemState backup is performed on a daily basis.

              Do I need to enable scavenging and aging on all servers or will only one be enough since it will be replicated?

              Comment


              • #8
                Re: (Reverse) DNS issue

                Are the zones AD-integrated? If so, I *believe* the scavenging settings will be propagated to all of the servers...
                Gareth Howells

                BSc (Hons), MBCS, MCP, MCDST, ICCE

                Any advice is given in good faith and without warranty.

                Please give reputation points if somebody has helped you.

                "For by now I could have stretched out my hand and struck you and your people with a plague that would have wiped you off the Earth." (Exodus 9:15) - I could kill you with my thumb.

                "Everything that lives and moves will be food for you." (Genesis 9:3) - For every animal you don't eat, I'm going to eat three.

                Comment


                • #9
                  Re: (Reverse) DNS issue

                  Yup, they are AD integrated.
                  Apologies for the many questions, I just want to make sure I don't do something I'll regret later. If there are no other suggestions I'll enable it on one of the servers and the respective AD integrated forward and reverse lookup zones.

                  Comment


                  • #10
                    Re: (Reverse) DNS issue

                    I still haven't enabled aging/scavenging, but came accross another issue today. I was unable to reach a particular site from one of our servers (I could reach it just fine on multiple other machines).
                    I did a nslookup www.site.com and received a DNS request timed out from our DNS server. A half an hour later it was working just fine.

                    Could this be in any way related to the previous problems?
                    Last edited by CypherBit; 11th June 2010, 12:44. Reason: Edited have to haven't.

                    Comment


                    • #11
                      Re: (Reverse) DNS issue

                      Is that record in any of the zones you've enabled scavenging on? If it's a site as in a website, which your dummy address suggests, then I would have thought not...
                      Gareth Howells

                      BSc (Hons), MBCS, MCP, MCDST, ICCE

                      Any advice is given in good faith and without warranty.

                      Please give reputation points if somebody has helped you.

                      "For by now I could have stretched out my hand and struck you and your people with a plague that would have wiped you off the Earth." (Exodus 9:15) - I could kill you with my thumb.

                      "Everything that lives and moves will be food for you." (Genesis 9:3) - For every animal you don't eat, I'm going to eat three.

                      Comment


                      • #12
                        Re: (Reverse) DNS issue

                        I'm yet to enable scavenging, yes it's a website, so it appears I have larger issues that previously believed.

                        Another thing I should probably mention is the fact that logons to the domain can at times take quite a bit of time, I've heared a badly configured DNS can be at fault for this as well.

                        Comment


                        • #13
                          Re: (Reverse) DNS issue

                          Originally posted by CypherBit View Post
                          I'm yet to enable scavenging, yes it's a website, so it appears I have larger issues that previously believed.
                          Perhaps, although there are perfectly innocent reasons why you may occasionally have a DNS query timeout.

                          Originally posted by CypherBit View Post
                          Another thing I should probably mention is the fact that logons to the domain can at times take quite a bit of time, I've heared a badly configured DNS can be at fault for this as well.
                          Yes it can, but a lot of things can too. You'll need to investigate the cause. Try to find patterns, such as time windows when it happens and doesn't happen, or specific workstations or users. When it does happen, check which DC the user authenticated against (%LOGONSERVER%). Check event logs on servers and clients for errors. Use Wireshark to see what's going down the wire.

                          Etc etc
                          Gareth Howells

                          BSc (Hons), MBCS, MCP, MCDST, ICCE

                          Any advice is given in good faith and without warranty.

                          Please give reputation points if somebody has helped you.

                          "For by now I could have stretched out my hand and struck you and your people with a plague that would have wiped you off the Earth." (Exodus 9:15) - I could kill you with my thumb.

                          "Everything that lives and moves will be food for you." (Genesis 9:3) - For every animal you don't eat, I'm going to eat three.

                          Comment


                          • #14
                            Re: (Reverse) DNS issue

                            gforceindustries, I'm revisiting this topic, since I finally got around to actually fixing my problems. I had aging, scavenging enabled for a while (about a week) now and nothing has happened.

                            While it probably shouldn't have scavenged the records by now (I have it set for 7, 7 days) it does nothing when I click Scavange Stale Resource Records. The Event that gets generated is this:

                            Code:
                            Event Type: Information
                            Event Source: DNS
                            Event Category: None
                            Event ID: 2502
                            Date:  26.7.2010
                            Time:  8:31:47
                            User:  N/A
                            Computer: DNS1
                            Description:
                            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.
                            For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
                            I checked the forward and reverse zones that have the stale records (from year 2007) and aging, scavening is enabled.

                            Comment


                            • #15
                              Re: (Reverse) DNS issue

                              Can anyone help me out with this one, I still see lots of records (for the same host) that's repeated dozens of times, the records go way back to year 2007.

                              How can I go about cleaning this up?

                              Comment

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