[Nagiosplug-help] check_http and missing DNS fallback

[Thomas Guyot-Sionnest]

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On 30/03/09 04:17 AM, Steffen Poulsen wrote:
> Hi,

Hi,

> Is there any way to make check_http fallback on dns service used (like
> other services at the machine)?

This problem is not specific to Nagios Plugins. If your DNS fail other
components might be affected with delays. This is an OS configuration
problem.

It is normal behavior on UNIX to test DNS servers listed in
/etc/resolv.conf in order with a rather long delay between them. If you
want a behavior more like Windows, install a local DNS cache (I use
Dnscache) configured to use all your DNS servers as "masters", then
point your resolv.conf to Dnscache (127.0.0.1). Dnscache will try all
servers in the "@" file quicker and cache the IPs.

http://cr.yp.to/djbdns/run-cache-home.html

> 
> I know there is  a ?-I? parameter for passing in the ip directly to the
> check, but this is not the behavior I?m after - I still want the check
> to be dynamic with regards to the IP address for the service.

I do all my tests using IP-based checks, and explicitly test dns
separately. On large setups in can be very annoying when your dns fail
while you rely on it for all your checks. :)

- --
Thomas
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