[Nagiosplug-help] check_dns oddity

[Bart Matthaei]

Hi,

when I use check_dns to query one of our nameservers, and the
nameserver isn't authoritive for the ipspace it's running on, it times
out.

When I did a tcpdump, and some log checking, it became clear to me
that check_dns was doing a reverse lookup of the IP the nameserver is
running on. But it's not querying the caching nameservers defined in
/etc/resolv.conf .. It's querying the nameserver I'm doing the check
on.

Now a lot of nameservers running BIND have recursive set to yes, so
there's no problem there.
But I'm running tinydns, and tinydns has no clue what-so-ever about
the reverse of it's own IP address.

Example:

./check_dns -H www.cysonet.com -s 62.58.71.5

The logs show me:

@400000003df85deb126db854 00000000000000000000ffffd9aa022a:a2dd:9313 - 000c 5.71.58.62.in-addr.arpa

Ofcourse, the check_dns time's out, because 62.58.71.5 isn't carying 
any information about 5.71.58.62.in-addr.arpa.

62.58.71.5 is our secondary nameserver running in another network 
not under our administration.

Now I did the same lookup on our primary nameserver, which IS authoritive 
for the space it's running on (217.170.2.0/23):

./check_dns -H www.cysonet.com -s 217.170.2.38

@400000003df85ebf16e76934 00000000000000000000ffffd9aa022a:a358:8c6a + 000c 38.2.170.217.in-addr.arpa
@400000003df85ebf16f301f4 00000000000000000000ffffd9aa022a:a358:8c6b + 0001 www.cysonet.com

Can anyone enlighten me on this issue ?

Kind Regards,

Bart Matthaei

p.s. I'm not a member of this list, so please keep the Reply-to intact
;)

-- 
Bart Matthaei               bart at cysonet.com

Cysonet Managed Hosting     t: +31 20 6822210
http://www.cysonet.nl/      f: +31 20 6822311