Re: [CentOS] DNS lookup delay with centos & postfix

On Wednesday 25 July 2012 17:47, the following was written:

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.

I believe the reason you noticed a faster response is because the second query used the cached information from the first look-up not because the second server is/was faster.

to verify this look at the TTL times in the response.