DNS problems this morning -

[Tim]

Tim:
>> I tested using dig and nslookup, I already knew that they tell which
>> server answered, they told me that the same one kept answering.


Chris Adams:
> Those tools are really for debugging of DNS itself, and they do not use
> the normal resolver library (or at least not in the normal way).  I
> believe the "host" command does use the normal resolver (like any other
> program).

Using the host command (i.e. host -v example.com), was no different than
using dig or nslookup, it always queried the first DNS server.

I do notice that having "options rotate" in my /etc/resolv.conf file is
upsetting my mail client (making it intermittently fail), so it does
have some effect.  And it doesn't seem to matter whereabouts I put the
option in the command file (before, or after, the name servers)  As part
of the test, I put two DNS servers in the resolv.conf file, one of which
cannot resolve my LAN addresses, and the mail client is using the LAN
mail server.

Unfortunately, that other DNS server doesn't provide logs (it's in the
modem/router), so I can't tell what it's doing for absolute certain.
But the mail client behaviour does point to the rotate option doing what
it ought to.

Oddly enough, it doesn't seem to be upsetting lynx, which should, also,
randomly be unable to resolve a LAN webserver address.

I'll have to try another test, later, when I have another computer with
a proper DNS server installed on it, so I can watch access logs on two
servers during queries.

-- 
[tim at localhost ~]$ uname -rsvp
Linux 3.6.6-1.fc17.x86_64 #1 SMP Mon Nov 5 21:59:35 UTC 2012 x86_64

All mail to my mailbox is automatically deleted, there is no point
trying to privately email me, I will only read messages posted to the
public lists.



-- 
[tim at localhost ~]$ uname -rsvp
Linux 3.6.6-1.fc17.x86_64 #1 SMP Mon Nov 5 21:59:35 UTC 2012 x86_64

All mail to my mailbox is automatically deleted, there is no point
trying to privately email me, I will only read messages posted to the
public lists.