plug timeout w/o Bind

[Marc Powell]

> -----Original Message-----
> From: nagios-users-bounces at lists.sourceforge.net [mailto:nagios-users-
> bounces at lists.sourceforge.net] On Behalf Of David Schlecht
> Sent: Friday, July 28, 2006 10:20 AM
> To: nagios-users at lists.sourceforge.net
> Subject: [Nagios-users] plug timeout w/o Bind
> 
> Hi All,
> 
> 
> 
> I'm running Nagios v2.2 on a suse linux without Bind.
> 
> When my first nameserver in resolv.conf fails, the
> 
> Nagios checks start timing out. I get a mix of timeout
> 
> errors and "no response" errors.
> 
> 
> 
> This isn't really a big surprise since relying on
> 
> resolv.conf is very slow when the DNS servers start
> 
> dropping off. Of course, the name resolution works
> 
> eventually but by then my 10-second timeout settings
> 
> have given up.
> 
> 
> 
> Has anyone using resolv.conf encountered and/or resolved
> 
> this? Is Bind a requirement because of this?

My comments --

- Don't rely on DNS at all. Use IP addresses. Why require a critical
infrastructure resource (monitoring) to depend on another potentially
fallable infrastructure resource (DNS) when you don't have to? If you
have a problem, how do you know if it's the device/service you are
monitoring or your DNS? Why spend the time determining that when you can
eliminate it as a factor?

- If you must rely on DNS then the only actions you can really take are
to
	- increase your timeout value to account for those times when
one or more of your DNS servers are unavailable.
	- load balance your nameservers such that a group answers for
the same IP. If one fails out the others will still answer. There are a
number of ways to do this with hardware/software or network
configuration.

- Running bind on the nagios box just moves the point of failure rather
than eliminating it.

--
Marc

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