Nagios checks and DNS queries

[Sean McAfee]

Steve Burton wrote:
> Dirk,
>
> my solution was to run a slave name server on the Nagios server itself , 
> restricted to only answer queries from localhost.
>
> Steve.
>
Why not set something like "options timeout:1 attempts:1" in 
resolv.conf?  From man resolv.conf:*

timeout:*/n/
sets the amount of time the resolver will wait for a response from a 
remote name server before retrying the query via a different name 
server. Measured in seconds, the default is RES_TIMEOUT (currently 5, 
see <resolv.h <http://linux.die.net/include/resolv.h>>).*

attempts:*/n/
sets the number of times the resolver will send a query to its name 
servers before giving up and returning an error to the calling 
application. The default is RES_DFLRETRY (currently 2, see <resolv.h 
<http://linux.die.net/include/resolv.h>>).

With the defaults, you're looking at 10 seconds (2 attempts, 5s apart) 
before it moves onto the next server.  Since 10 seconds is the default 
timeout for those checks, you'll always hit a timeout unless the DNS 
server becomes responsive again.

-- 
Sean McAfee
System Engineer

Collaborative Fusion, Inc.
 smcafee at collaborativefusion.com
 412-422-3463 x 4025

5849 Forbes Avenue
Pittsburgh, PA 15217

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