[CentOS] DNS lookup delay with centos & postfix

Wed Jul 25 22:29:08 UTC 2012
Steve Lindemann <steve at marmot.org>

On 7/25/2012 3:58 PM, Tom Brown wrote:
>> dig uses resolv.conf and no timeouts are configured there.  I don't know
>> there the OS would have a default configured or what it is.  Another
>> reply indicated there would be a 5 second delay.  That seems a bit high
>> to me.
>> I used dig from the email svr command line with the primary DNS svr up
>> and (naturally) it pulled from there as normal.  Then I downed the
>> primary DNS svr, saw the nagios check fail and tried again.  The same
>> dig lookup was actually faster and pulled from the secondary DNS svr
>> just fine.  And, again, the nagios alert cleared as soon as the primary
>> DNS svr was back online.
>> For both tests I used:  dig mx google.com
> i would always have a timeout in your resolv.conf rather than relying
> on the OS default.
> Set that to 1 second and test again to see if there is any difference.

and that sounds like the best solution so far.  I hadn't considered 
that... haven't look at that file in ages.

I do like knowing why something doesn't work, but I'm good with just 
getting it to work too.  I'll give this a try, thanks!