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  • Forward a PTR to another DNS Server?

    Does any one know if it is possible to Forward a PTR request (Reverse LookUp) to another DNS, if the PTR is not found on that DNS it would forward the PTR resolving to a different DNS, like you can do for a Forward Lookup Zone?

  • #2
    Re: Forward a PTR to another DNS Server?

    It depends. Are you taking about PTR in a zone that is configured on the DNS server or a PTR not belonging to any of the reverse lookup zones configured on the DNS server ?
    Guy Teverovsky
    "Smith & Wesson - the original point and click interface"

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    • #3
      Re: Forward a PTR to another DNS Server?

      Originally posted by guyt View Post
      It depends. Are you taking about PTR in a zone that is configured on the DNS server or a PTR not belonging to any of the reverse lookup zones configured on the DNS server ?
      both, but mainly a PTR that does not exists on the server but the zone does.
      but I would like knowing also if it is possible to forward a PTR that the zone does not exists .

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      • #4
        Re: Forward a PTR to another DNS Server?

        PTRs are trated almost the same as A records when it comes to DNS zones, meaning that if a PTR belongs to a zone that is configured on the DNS server, but is not present in the zone, you will get NXDOMAIN (Not existant Domain) as an answer.

        Notice how PTRs are actually queried:

        Code:
        [[email protected] /]# nslookup 10.10.10.10
        Server:         127.0.0.1
        Address:        127.0.0.1#53
        
        ** server can't find 10.10.10.10.in-addr.arpa: NXDOMAIN
        The IP address is translated to a standard "10.10.10.10.in-addr.arpa" query, meaning that it will start from "in-addr.arpa" zone and will try to drill down chasing the delegated zones till it finds the answer (or not).

        Reverse zones can be delegated too, just like forward zones (right-click any reverse lookup zone and you will see that all the delegation options of forward zone are there. You can also have secondary and stub reverse lookup zones - nothing is stopping you from configuring those and it is allowed by DNS standards.

        Reverse lookup resolution behaves the same as forward lookups, which means that if the DNS server is authoritative for the zone, it will answer. If not, it will try to use forwarders (same forwarders you configure for for forward zones - actually those a global and not forward specific).
        Guy Teverovsky
        "Smith & Wesson - the original point and click interface"

        Comment


        • #5
          Re: Forward a PTR to another DNS Server?

          is it possible delegating a zone to a DNS server (AD) out side of the forest (different forest) - I never actually tried it b4.
          in my case the Secondary/Stub zone won't do me any good.
          Last edited by Akila; 28th July 2008, 18:31.

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          • #6
            Re: Forward a PTR to another DNS Server?

            Originally posted by Akila View Post
            is it possible delegating a zone to a DNS server (AD) out side of the forest (different forest) - I never actually tried it b4.
            in my case the Secondary/Stub zone won't do me any good.
            That's what forwarders and conditional forwarders are for. You only delegate subdomains.
            Last edited by Garen; 29th July 2008, 00:05.

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            • #7
              Re: Forward a PTR to another DNS Server?

              Originally posted by Akila View Post
              is it possible delegating a zone to a DNS server (AD) out side of the forest (different forest) - I never actually tried it b4.
              in my case the Secondary/Stub zone won't do me any good.
              Sure you can. But I am not sure what you are trying to achieve. Can you shed some light about what you are trying to solve ?
              Guy Teverovsky
              "Smith & Wesson - the original point and click interface"

              Comment


              • #8
                Re: Forward a PTR to another DNS Server?

                Originally posted by guyt View Post
                Can you shed some light about what you are trying to solve ?
                I knew it would be inevitable - I was to lazy posting the entire story

                ok , here it goes.
                I have a production DNS/AD - prod.com
                I just Migrated a a small company into our Domain - other.com

                Along with the Migration I migrated their Users/Groups/WorkStations and few Server.
                Many of the Servers remained in their old domain which would be some day a DMZ with their old other.com domain and the trust would be broken, but in the mean time they need some resources on the old domain.

                here is the thing, the WS are all configured to work with our AD/DNS, since they are now part on prod.com.
                every DNS request for resources on other.com is forwarded to their AD/DNS.
                the problem starts when they need a PTR resolving, their WS are configured to query my DNS, my question is how can I forward a PTR request (if record not found, but the PTR zone for that Scope exists in my DNS) for those Users/WS/whatever to thier DNS server in their Domain?
                I hope I cleared my self better now.
                Last edited by Akila; 29th July 2008, 09:39.

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                • #9
                  Re: Forward a PTR to another DNS Server?

                  DNS server properties, Forwarders, DNS domain, New and type the subnet
                  10.2.5.x subnet. which will solve the problem


                  have attached screen shot for ur reference
                  Attached Files

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                  • #10
                    Re: Forward a PTR to another DNS Server?

                    Originally posted by balasat View Post
                    DNS server properties, Forwarders, DNS domain, New and type the subnet
                    10.2.5.x subnet. which will solve the problem


                    have attached screen shot for ur reference
                    two things.
                    1) are you sure this would work? since those are meant for forwarders not reverse zones?
                    2) I have that Zone in my DNS , I just need the DNS to forward records that do not exist to an alternate DNS, if I would do what you suggested my Entire prod.com would be forwarded to that DNS server regardless if the record is there or not in my DNS.

                    Comment


                    • #11
                      Re: Forward a PTR to another DNS Server?

                      Originally posted by Akila View Post
                      two things.
                      1) are you sure this would work? since those are meant for forwarders not reverse zones?
                      Forwarders are called this way because they "forward" unresolvable queries to another server, not because they do it only for forward zones - forwarders can forward queries for records in both forward and reverse lookup zones.
                      Yes - it will work. The only thing I'm not sure is the format of the reverse lookup zone name. As far as I know, instead of "192.168.0.x Subnet" you need to enter "0.168.192.IN-ADDR.ARPA"


                      Originally posted by Akila View Post
                      2) I have that Zone in my DNS , I just need the DNS to forward records that do not exist to an alternate DNS, if I would do what you suggested my Entire prod.com would be forwarded to that DNS server regardless if the record is there or not in my DNS.
                      This is conditional forwarding, meaning that only queries for records in "0.168.192.IN-ADDR.ARPA" zone will be forwarded to the server you specify.

                      Bottom line: there is almost no difference between forward and reverse lookup zones when it comes to name resolution.
                      Guy Teverovsky
                      "Smith & Wesson - the original point and click interface"

                      Comment


                      • #12
                        Re: Forward a PTR to another DNS Server?

                        the only thing is, if I do a conditional forward for the PTR zone, it would effect the entire prod.com, as I mentioned that zone does exist
                        in my DNS and WS/Servers in the prod.com are using it to resolve , what I need is only for records that do not appear in the zone then it would conditional forward to whatever i like.
                        is that possible?
                        e.g let's say I got a zone in my Production of "0.168.192.IN-ADDR.ARPA" let's say that I use from 192.168.1.x - 192.168.100.x.
                        2 questions.
                        case 1. how do I forward whatever is from 192.168.101.x onwards?
                        case 2: how do I forward a record in 192.168.12.x that I am not using at the moment
                        ( but still part of the range 192.168.1.x - 192.168.100.x) and I would make sure it would not be used (preventing clashes)?
                        Last edited by Akila; 29th July 2008, 18:17.

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                        • #13
                          Re: Forward a PTR to another DNS Server?

                          I don't see how this would work. Zones take priorety over Forwarders, if the zone exits without the record you're looking for, it will never send it off to the Forwarder.

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                          • #14
                            Re: Forward a PTR to another DNS Server?

                            Do you have a single 192.168.x.x reverse lookup zone or multiple 192.168.0.x-192.168.100.x zones ?

                            If you have a single 192.168.x.x class B zone (aka 168.192.in-addr.arpa), you will not be able to forward queries about ANYTHING in this zone (including 192.168.101.x), as your DNS servier is authoritative for all the records in this zone.

                            If you have 101 class C zones defined (192.168.0.x - 192.168.100.x, aka "0.168.192.in-addr-arpa" - "100.168.192.in-addr.arpa"), then your DNS server is not authoritative for "192.168.101.x" zone and will be able to forward the queries for this zone to another DNS server.
                            Guy Teverovsky
                            "Smith & Wesson - the original point and click interface"

                            Comment


                            • #15
                              Re: Forward a PTR to another DNS Server?

                              Hi,


                              wht abt conditional forwarding.
                              http://support.microsoft.com/kb/304491

                              Rgds

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