auth: Warning: DNS lookup took 1.550 s

[LuKreme]

On 04 Feb 2015, at 03:38 , ML mail <mlnospam at yahoo.com> wrote:
> I am running a dovecot and proxy server on two different virtual machines and on the dovecot proxy server I see around 5-6 times per day the following warning:
> 
> Feb 03 16:15:12 auth: Warning: proxy(email at domain.com,xxx.xxx.xxx.xxx,<ABC123456789>): DNS lookup for mailboxserver.domain.com took 1.550 s

If you are seeing a warning that dans lookup took 1.5 seconds 5-6 times a day, why are you concerned?

> I do not really understand how from time to time DNS queries are slow,

Because from time to time, queries are slow. A hiccough in the line, the server is slightly busy doing something else. There’s a lot of bandwidth during those 1.5 seconds being used. It could be anything. If you were seeing hundreds of these warning, or if the times were over 5 seconds, then I’d worry.

> I tried replicate this issue using dig to resolve the same DNS entry and it was always very fast. Is there any way I can debug better this issue? or is this nothing to worry about really?

I would not worry about it based on these numbers.

-- 
there were far worse things than Evil. All the demons in Hell would
torture your very soul, but that was precisely because they valued souls
very highly; Evil would always try to steal the universe, but at least
it considered the universe worth stealing. But the grey world behind
those empty eyes would trample and destroy without even according its
victims the dignity of hatred. It wouldn't even notice them. --The Light
Fantastic