[CentOS] DNS lookup delay with centos & postfix
Steve Lindemann
steve at marmot.org
Wed Jul 25 22:29:08 UTC 2012
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!
--
Steve
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