[lug] dns weirdness

[Stephen Queen]

On 12/19/06, Ben <bluey at iguanaworks.net> wrote:
> 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 205.171.3.65" 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,
>
> Ben
> _______________________________________________

When I was having the same issues back in March,  I got this response.
###################################
On 12/5/05, Ken Kinder <kkinder at gmail.com> wrote:
>
> I don't have that modem anymore, but I recall running something like
> nslookup -timeout=3 (domain) and watching the modem intermittently
> fail to resolve names.
>
> I'd urge you to just use a real name server or get a new modem. I had
> this same problem and I attributed it to the flaky modem. Qwest,
> needless to say, was of no help at all.
>

This may well be the culprit: ActionTEC modems don't like IPv6:

http://balrog.nmglug.org/pipermail/nmglug/2005-August/001185.html

I would still just bypass the modem for DNS. But it looks like it
works OK for IPv4, which explains why the problem doesn't occur for
Windows boxes and therefor Qwest's general user base.
########################################

I bought a Zoom modem and have had no problems since.

Steve