check_dns problems

[Subhendu Ghosh]

On Mon, 22 Mar 2004, Robert Nelson wrote:

> Hello,
> 
> I've used the check_dns plugin for quite awhile now at another job, and
> it worked flawlessly. When I got to my current job, I threw up Nagios
> and lo and behold, the first two services I put in to showcase the
> system were DNS and are showing red nearly all the time. Whoops!
> 
> I'm using check_dns on two freeBSD servers. Check_dns is reporting an
> effective downtime of 99% (the few times I get a recovery notice, I also
> get a failure notice within 5-10 minutes). At the same time, our entire
> office uses these two DNS servers exclusively, as well as all our
> clients, and no-one reports any DNS problems.
> 
> This has been going on for nearly a month now. I can't explain it at
> all. Using check_dns from the command line rapidly (up arrow, enter, up
> arrow, enter, etc.) gives me *maybe* a 2 in 10 failure rate. Doing
> nslookup's to the same servers gives possibly a 1/100 failure, altho
> some queries take more than the 10 seconds that the plugin times out in.
> At the same time, constant pings between the nagios and DNS servers work
> 100%. I have this problem with BOTH dns servers.
> 
> Setup is...
> 
> Nagios:
> Nagios v1.2
> check_dns (nagios-plugins 1.3.1) 1.8.2.3
> Red Hat v8.0
> Apache 2.0.4
> 
> DNS Servers:
> FreeBSD 4.7-RELEASE-p3
> named 8.3.3-REL
> 
> Thanks!
> 


Do you have query logging enabled on the DNS servers and can see the 
relative timing of the requests?

Are the check_dns checks for authoritative or recursive records?

Any problems with load on nagios or the dns systems?
-- 

-sg



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