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  • DHCP Question...

    I have an NT Domain (let's call it ABC) and a Win 2K3 domain (abc.local).

    They have a two-way trust between them.

    On the NT Domain:
    Servers have static 10.1.1.x IP addresses. Clients receive IP addresses using a DHCP server with a scope of 10.1.4.x . DHCP works fine on this domain.

    On the Win2K3 side:
    Servers have static 10.1.10.x IP addresses. Clients cannot seem to get 10.1.4.x addresses from the DHCP server on the NT side.

    There is no router between these domains.

    When a client (with abc.local specified as the domain) tries to boot, it does not get a 10.1.4.x IP address, it receives an APIPA address. I've done a packet trace of the login process and I found that I only see DHCP Discover packets. There is not Offer, Request or Accept. This indicates to me that my client is not finding a DHCP server.

    Does this seem right? Do I need to set up a 2nd DHCP server with a different scope on my Win2K3 domain? If so, do I need to worry about my ABC domain clients getting their IP address from the abc.local DHCP server?

    Any thoughts would be very welcome.

    Thanks.

  • #2
    Re: DHCP Question...

    Can any of the servers on the 10.1.10.x subnet ping servers on the 10.1.1.x subnet?

    Mostly likely cause is that there just isn't a route between the two subnets. Might be easiest to just set up a second DHCP server on the 2k3 side to issue addresses.

    I guess you're doing DNS seperate on each site too yeah?

    Hope this helps

    Dean

    Comment


    • #3
      Re: DHCP Question...

      Hi Dean. Thanks for your reply.

      Yes, from a 10.1.10.x server, I can ping all of the 10.1.1.x servers. I can ping them by name even not just by IP address.

      That's one of the things that has me confused.

      And yes, they each have their own DNS server.

      I'm not opposed to setting up a DHCP server on the Win2K3 side. I just don't want to compound the problem with another layer of complexity. Of course, that may simply be the fix.

      I just expected that this would work with only 1 DHCP server.

      Comment


      • #4
        Re: DHCP Question...

        TBH I would of thought the same thing, that it'd work fine with 1 DHCP server with a trust in place.

        You could try giving one of the workstations (if accessable) a static ip and see if you can then ping the DHCP server. I think the best way forward is to prove/make a route between the 2k3 workstation subnet and the subnet containing the DHCP server.

        I can imagine how annoying this is for you, 9 times outta 10 it's something simple too

        Hope you get it sorted mate!

        Dean

        Comment


        • #5
          Re: DHCP Question...

          Hello,
          A simple but useful test is to plug a network cable used by desktop witch works fine with DHCP into a desktop with problems.
          What about the dhcp client? is this service started on desktops from abc.local?
          The second DHCP servers are only need for backup. In this cause the scops should be designed properly, in other way a big mess will result.
          Regards,
          Csaba
          Regards,
          Csaba Papp
          MCSA+messaging, MCSE, CCNA
          ...............................
          Remember to give credit where credit is due and leave reputation points where appropriate
          .................................

          Comment


          • #6
            Re: DHCP Question...

            If I give a laptop on the abc.local domain a static IP address of 10.1.4.x then I can ping servers on the ABC domain with no problem (including the DHCP server).

            For whatever reason, the problem is that a computer on the abc.local side of the equation cannot find my DHCP server (at 10.1.1.3).

            Perhaps, the solution has to do with the way DHCP and DNS are integrated within Active Directory?

            Maybe it can't find the DHCP server since it is on the NT 4.0 domain and my client is specifying a Win2K3 domain in its configuration?

            Comment


            • #7
              Re: DHCP Question...

              Thanks Csaba,

              I have been using a network cable (and wall jack) that works with the DHCP server when using the ABC domain.

              I guess I'm not sure if I need to do anything to the DHCP server on the NT domain in order to get it to be able to recognize (and give IP addresses to) clients on the Win2K3 side of my network.

              I know that DHCP servers need to be authorized within AD. Maybe that's the problem - I did not authorize my NT 4.0 DHCP server within AD.

              Comment


              • #8
                Re: DHCP Question...

                There is nothing regarding to AD integrated dhcp and dns servers.
                Even a Linux dhcp server should work properly.
                Cheack the DHCP client service on desktops, and make sure that it is started.
                regards,
                Csaba
                Regards,
                Csaba Papp
                MCSA+messaging, MCSE, CCNA
                ...............................
                Remember to give credit where credit is due and leave reputation points where appropriate
                .................................

                Comment


                • #9
                  Re: DHCP Question...

                  Yes, it is started.

                  I should mention that the laptops I'm using have been used successfully as clients on my NT domain (ABC). I'm currently migrating them to the abc.local domain.

                  Comment


                  • #10
                    Re: DHCP Question...

                    Strange..
                    Is your DHCP server working properly? (run ipconfig /release, ipconfig /renew on a workstation from ABC NT domain. Are there free IPs in the pool of the scope?
                    Regards,
                    Csaba Papp
                    MCSA+messaging, MCSE, CCNA
                    ...............................
                    Remember to give credit where credit is due and leave reputation points where appropriate
                    .................................

                    Comment


                    • #11
                      Re: DHCP Question...

                      Yes. /renew and /release work as they should.

                      I have more than enough free IPs in the scope. I have only about 70 users and my scope is 10.1.4.x (all of it).

                      It's very bizarre.

                      Another strange thing. When converting the laptops over to connect to the new domain, I had no initial connectivity problems.

                      The scenario was as follows:

                      I logged on to my old NT 4.0 domain (ABC)
                      I changed the domain information on the laptop to abc.local
                      Restarted
                      Logged in to the new domain
                      I accessed SQL databases on the new domain, browsed the internet, etc. on the new domain with no trouble.

                      Shortly, and I can't say when maybe a couple of days, I began to have this problem. This is the second laptop that had this issue. Maybe the old lease (IP address) was active on the machine and then ran out, thus causing the problem? The leases are set for 7 days. It's just a guess.

                      Thanks.

                      Comment


                      • #12
                        Re: DHCP Question...

                        Based on your latest information:
                        Desktops from the Win2k3 domain are able to work with DHCP from Nt4 domain, at least for a short period of time. After each restart the dhcp client try to renew its IP address.
                        it is really hard to provide a valid answer.
                        My opinion is that configure a new DHCP server in your win2k3 domain, after that remove the old one from your NT4 domain. All these actions should take less than 30 minutes. (Maybe 10 if you work quikly )
                        You should do it sooner or later

                        Csaba
                        Regards,
                        Csaba Papp
                        MCSA+messaging, MCSE, CCNA
                        ...............................
                        Remember to give credit where credit is due and leave reputation points where appropriate
                        .................................

                        Comment


                        • #13
                          Re: DHCP Question...

                          Csaba,

                          That makes the best sense. Hopefully, I will not have the same problem but in reverse where my NT domain users cannot find the Win2K3 DHCP server!

                          Thanks for your help!

                          Comment


                          • #14
                            Re: DHCP Question...

                            Well, I set up a new DHCP server on my abc.local domain using a 10.1.8.x scope. My NT domain DHCP server uses a 10.1.4.x scope.

                            My client machines on the abc.local domain can find the new DHCP server and correctly login.

                            The only problem, and I guess it doesn't really matter, is that my NT domain machines are also finding it.

                            I booted an NT laptop and logged in. It renewed its 10.1.4.x address correctly. I did an ipconfig /release and then rebooted it again. When I logged in it now had a 10.1.8.x address - i.e., it found the new DHCP server.

                            As I said, it's probably not the end of the world. I can't think of any possible problems with that scenario (unless you can think of one?!).

                            I'll probably decommision the old NT DHCP server at some point anyway.

                            Thanks for everyone's help!

                            Comment

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