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DHCP binding on wrong NIC

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  • DHCP binding on wrong NIC

    Ok, I've had a few posts on here of late with some NIC issues...

    I think I've finally spotted one of the concerns.

    DHCP is not enabled on the primary NIC for our SBS 2008.

    1. Yes the service is running
    2. Yes in the DHCP snap in it binded (proper word?) to the SBS 2008 server
    3. Yes I know SBS 2008 is supposed to only have one NIC!

    Some issues this week had me suspected the onboard NIC was bad. Simple enough we took NIC #1 offline eventually removing the static references so there was no conflict...disabled the NIC #1 in devices and then activated NIC #2 (onboard also) and setup the static values as before. Same IP, same DNS, ect...

    But I noted in the detail view (also can be found via ipconfig/all) that DHCP is "disabled" on the NIC #2.

    So I "enabled" NIC #1 yet again and guess what...DHCP is bound to that NIC..

    How do I fix this?

    "the google" is not treating me well on this topic...most everything has todo with VM, non-SBS, ect.
    Attached Files

  • #2
    Re: DHCP binding on wrong NIC

    You're looking at the wrong thing. The DHCP service and the DHCP client are two different components, just as the DNS server and the DNS client are different components (even when they're on the same server). The server NIC settings as displayed in ipconfig /all are for the DHCP client component and it should not be enabled for DHCP, it should have a static ip address.

    THE DHCP server component should be bound to the ip address(es). You do this from the DHCP server console.

    BTW, the IPv6 DHCP client listed in ipconfig /all shows that the DHCP client for IPv6 is enabled, which is perfectly normal. Again, because you don't have an IPv6 network.
    Last edited by joeqwerty; 10th October 2012, 23:09.


    • #3
      Re: DHCP binding on wrong NIC

      Yea I'm an idiot...I figured that out about and hour ago and just haven't had time to post back.

      The issue I have now is that although DHCP appears to be running and binded in the DHCP snap-in the the correct NIC none of our clients are getting IPs now.

      I checked to make sure there was not a rouge DHCP server (I've had a few linksys wireless routers around here with DHCP turned off) but that is not the case.

      I'm really scratching my head on this one!

      Set client static and I'm good all day, put them in client DHCP mode they are off the net...but on the server side everything DHCP looks to be working!


      • #4
        Re: DHCP binding on wrong NIC

        Here's what I would do at this point:

        Install and run Microsoft Network Monitor on the server, set a display filter for DHCP, start a capture, run ipconfig/release and ipconfig/renew on one of the clients, and look at the capture for the DORA conversation (DHCP Discover, Offer, Request, Acknowledge).

        Based on what you see (or don't see) in the capture you may find some clues as to what's going on.

        Also, verify one more time that DHCP is running, authorized, has a valid scope, and is bound to the correct ip address.


        • #5
          Re: DHCP binding on wrong NIC

          Can you please post screenshots of the following

          DHCP Server Console expanded.
          Right Click on IPv4 and select properties. Go to the Advanced Tab. Click on Bindings. Post this.
          Your Services.msc console showing the DHCP services.

          Are your switches running VLAN's? Is the new NIC using the same port as the old one?