[dns-operations] weird DNS problem

[Stephane Bortzmeyer]

On Wed, Jun 26, 2013 at 11:15:32PM -0500,
 alex flores <alex at mordormx.net> wrote 
 a message of 58 lines which said:

> One more weird thing is that just as the problem appeared, just
> dissapeared from the dns affected and it start to work correctly,
> but now we received the report from another dns....  So it looks
> like the condition that block the dns communication dissapear and
> then apply to another dns.

So it smells like a network problem. They are typically transient.

> <alejandro.flores at mexis.net>: Host or domain name not found. Name service error
>     for name=mexis.net type=MX: Host not found, try again

You have only two authoritative name servers, in the same /16 and the
same AS. From traceroute, they also seem to be in the same physical
location. That is not enough to providence resilience and reliability.

A network issue with this prefix/AS/location is sufficient to explain
the symptoms you describe. DNS depends on IP, remember.