[lug] dns weirdness

Ben bluey at iguanaworks.net
Tue Dec 19 08:49:27 MST 2006

Thanks for all the replies on my DNS weirdness. The problem magically 
went away after I lost my internet connection and restarted the dsl modem.

My leading theory is that qwest's dns servers stopped working (I could 
ping them though), but my actiontek kept a good cache of most sites I 
wanted, so I could dns resolve through the router, but not directly. 
Since the windows clients had the dsl modem in the dns server list, 
that's how they were working. MX records failed because they weren't 
being cached? I think this explains the behavior I was seeing, except 
that no one else was having problems with qwest's servers.

For the record, I was running "host -t MX" and not "host -T MX" as I 
posted. The man pages says -T prints time-to-live values. I am running 
dnsmasq, to it isn't clear why dnsmasq didn't cache the names as well as 
the actiontek. Also, I cannot blame the dsl modem's dns server  for the 
command "host www.google.com" failing since I'm connecting 
directly to the qwest dns server.

I am curious about tcp vs udp. Maybe linux uses one and windows the 
other and for some reason my dsl modem (or quest) was dropping udp or 
something? Next time this happens I'll use nslookup and verify what 
exactly what windows is seeing. And host -u to force tcp on dns queries.

Thanks for the help,


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