Ad-hoc wireless DNS hell

June 1, 2005 8:45 PM

Why does the client machine on an ad-hoc wireless network on XP get DNS issues that the host machine doesn't?

Two machines, both running XP. Just a temporary thing, so we set up a wireless network with a USB adapter at the desktop end and the internal dingus on the laptop end, running an ad-hoc network and XP's internet connection sharing. Everything seems okay, the laptop can connect and do web stuff, but it gets DNS errors on sites that return fine on the desktop. I wouldn't much care except that metafilter is one of these sites.

posted by ROU_Xenophobe to computers & internet (2 comments total)

Funny, same thing happened to me with ICS. The machine behind the ICS gateway timed out on lots of sites -- Metafilter, Netflix, Amazon. My problem was not a DNS issue because domains were resolving fine, but irrespective of what caused it those sites would not load. For whatever reason, Internet Explorer was slightly more successful than Firefox in attempting to connect to Metafilter et al but it still sucked.

I fixed it by downloading and installing Privoxy on the gateway machine and configuring the client machine's browser to work through that. Not particularly elegant but it got the job done.
posted by mmcg at 11:57 PM on June 1, 2005

The problem is simple -- the host machine is either stating that it'll relay DNS, and isn't, or is stating that it will pass a DNS address in the DHCP information, and isn't.

Quick test: On the client machine, start, run, cmd.exe (enter), then type "ipconfig /all". See what the DNS server is listed as. Do the same on the host.

If the Client's DNS address is the hosts IP address, the problem is with the host, which is claiming to do DHCP relay, but isn't. This might be a configuration problem on the host, or just broken software

If the Client doesn't have a DNS address, the host isn't telling it what it is. Usually, this is a DHCP configuration problem on the host.

The workaround -- find out what the DNS server address is on the host. Tell the client machine that number. That way, it gets around both problems, by contacting the DNS server directly.
posted by eriko at 4:42 AM on June 2, 2005