[vox-tech] Strange DNS lookup failures (Ubuntu Fiesty)

[Rick Moen]

Quoting Bill Kendrick (nbs at sonic.net):

> I ran a 'ping sonic.net' (Sonic is our DSL provider), and noticed this:
> 
> ...
> 64 bytes from www.sonic.net (209.204.190.64): icmp_seq=298 ttl=250 time=18.7 ms
> 64 bytes from www.sonic.net (209.204.190.64): icmp_seq=299 ttl=250 time=19.0 ms
> 64 bytes from 209.204.190.64: icmp_seq=300 ttl=250 time=17.1 ms
> 64 bytes from 209.204.190.64: icmp_seq=301 ttl=250 time=17.4 ms
> 64 bytes from www.sonic.net (209.204.190.64): icmp_seq=302 ttl=250 time=18.4 ms
> 64 bytes from www.sonic.net (209.204.190.64): icmp_seq=303 ttl=250 time=17.2 ms
> ...

Wow, that's pretty weird (and no, I haven't seen that before, including
on my Xubuntu laptop).  But:

I notice that your two "nameserver" IPs in /etc/resolv.conf are a
customer-facing nameserver at Sonic.net (NS1.SONIC.NET) and an IP 
at Sprintlink that has no reverse DNS (no FQDN that points to it).
I have a very strong hunch that therein is your problem.  I suspect 
you have the IP address (208.2.224.33) miscopied, or missing a digit, or
something, because, you see, the IP you specified turns out, for
whatever reason, to be not doing DNS at all:

  $ dig linuxmafia.com @208.2.224.33

  ; <<>> DiG 9.3.2 <<>> linuxmafia.com @208.2.224.33
  ; (1 server found)
  ;; global options:  printcmd
  ;; connection timed out; no servers could be reached
  $

So, I suspect that a minimal fix would be to substitute for 208.2.224.33 
some different nameserver IP that's network-nearby and verified to be
functional.  Like, for example, NS2.SONIC.NET.  Which, oddly, turns out
to be IP 208.201.224.33.  ;->

(I suspect somehow the second set of digits somehow got mangled from the
correct "201" to "2".  There's your problem.)


Just as an afterthought, if you want to go beyond the _minimal_ fix, you
might want to run your own caching nameserver right on your workstation,
and change /etc/resolv.conf to have "nameserver 127.0.0.1" instead of
the existing pair (which you could comment out).  The pdnsd caching-only 
nameserver package would be pretty good for that purpose, and is
dead-simple -- and you will suddenly have local resolution of DNS names,
rather than having to query them across your DSL.

Just a thought.

-- 
Cheers,                     Peter G. Neumann:  "Mars has been a tough target."
Rick Moen                   Harlan Rosenthal:  "That's because the Martians keep
rick at linuxmafia.com         shooting things down."   RISKS Digest, v. 20, #59&60