3 Replies Latest reply on Jun 3, 2013 2:17 PM by daniel.blackmon

    How do I get DNS to work via DHCP on my AP clients?

    tmcc1961 New Member

      I have my BSAP units configured for DHCP and my vWLAN server setup statically with my DNS IP addresses. I'm using a NetVanta 1234 PoE switch for DHCP and have Option 43 configured, as well as my Primary and Secondary DNS IP addresses. When a client registers with an AP, it recieves an IP address from the NetVanta but no DNS IP address. WIthout the DNS address, my clients cannot get out to the internet.

       

      Any ideas???

        • Re: How do I get DNS to work via DHCP on my AP clients?
          kennethfernandes Employee

          After the client registers/authenticates, the IP address, gateway, and DNS servers are going to come from the DHCP server. In this case the DHCP server is the a NetVanta 1234 PoE switch. The question is, is the DHCP server sending the DNS addresses in the DHCP offer or not? You could perform a traffic capture on the wired interface of the access point while you obtain an IP address (status>details>diagnostics>AP traffic capture). Then using wireshark take a look at the DHCP offer in the traffic capture to see if the DNS addresses are included. What if you put a wired client in that same vlan? Does this happen to all clients or can it be narrowed down to a specific client type such as windows XP? Check out this hotfix for windows XP where options such as DNS addresses might not get recognized on a windows XP client when the DHCP server offer included option 43:

           

          Some DHCP Options are not recognized on a Windows XP SP3-based client computer when the DHCP server offer includes option 43

          • Re: How do I get DNS to work via DHCP on my AP clients?
            olivertwisted Employee

            tmcc1961, you may be mixing up DHCP for the APs and DHCP for the clients.

            My apologies if this is something you know...

            The APs use DHCP to get their IP address and gateway, and the APs can use option 43 to find the vWLAN server so that they can register and get their config.

            The clients do not learn their DNS server(s) from the vWLAN server.

            The DHCP scope for the clients subnet (vlan) would need to include the DNS server(s) which you want the clients to use.

            Frequently, the AP's IP address and the clients are on different subnets, so a different DHCP scope would be involved.

             

            If you are still having an issue, you could post your DHCP config from the 1234.

            If it includes DNS servers, are those servers reachable from the client subnet? (ping, tracert)

             

            Ken's point is also valid.

            • Re: How do I get DNS to work via DHCP on my AP clients?
              daniel.blackmon Employee

              tmcc1961

               

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