Okay, so I have these two machines hanging off of an access point which is connected via WDS to another access point, which is then connected to a wired LAN, router, and out to the series of tubes...
One of the two machines works just fine... but the other can't do DNS lookups. It doesn't matter what IP address I stuff into the workstation, or which DNS servers I tell it to use. If it attempts a DNS lookup at all, it fails.
It looks as if the DNS transaction is making it through the router. In this case, the misbehaving workstation has ip 192.168.2.31.
Router Internal Interface:
14:18:58.078610 192.168.2.31.1060 > $DNS_SERVER.domain: 5+ A? cnn.com. (25)
14:18:58.095962 $DNS_SERVER.domain > 192.168.2.31.1060: 5 4/0/0 A 126.96.36.199, A[|domain] (DF) [tos 0x40]
14:19:00.065339 192.168.2.31.1061 > $DNS_SERVER.domain: 6+ A? cnn.com. (25)
14:19:00.082952 $DNS_SERVER.domain > 192.168.2.31.1061: 6 4/0/0 A 188.8.131.52, A[|domain] (DF) [tos 0x40]
Router External Interface:
14:18:58.078657 $EXTERNAL_IP.1060 > $DNS_SERVER.domain: 5+ A? cnn.com. (25)
14:18:58.095935 $DNS_SERVER.domain > $EXTERNAL_IP.1060: 5 4/0/0 A 184.108.40.206, A[|domain] (DF) [tos 0x40]
14:19:00.065396 $EXTERNAL_IP.1061 > $DNS_SERVER.domain: 6+ A? cnn.com. (25)
14:19:00.082907 $DNS_SERVER.domain > $EXTERNAL_IP.1061: 6 4/0/0 A 220.127.116.11, A[|domain] (DF) [tos 0x40]
Windows Firewall is OFF, and there are no other firewall programs installed. You can see the DNS answer being sent from the router to the workstation in red.
So... what gives? Either the answer packet just isn't getting sent over the wireless link (but all other traffic is), or the workstation is receiving the answer and not understanding it, or possibly something else?
If I tell the browser to use the on-site squid proxy, everything works fine because the proxy does the DNS lookup. Every other machine on the network is working just fine, which leads me to believe the problem lies with this machine. It's brand new, just built the other day.
It's bizarre, so I'm hoping one of you sysadmins here will have seen something like this in your travels.