Mailinglist Archive: opensuse (1420 mails)

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Re: [opensuse] optimizing resolv.conf
  • From: Per Jessen <per@xxxxxxxxxxxx>
  • Date: Fri, 03 Jan 2014 17:41:02 +0100
  • Message-id: <la6p7a$lhj$1@saturn.local.net>
Anton Aylward wrote:

Greg Freemyer said the following on 01/03/2014 10:20 AM:
On Fri, Jan 3, 2014 at 10:13 AM, James Knott <james.knott@xxxxxxxxxx>
wrote:
Anton Aylward wrote:
From my POV having an old or tiny box dedicated to DNS with a
couple
of gigs of memory[1] with a -ing cache and a -ing long timeout will
'outperform' all of the above after a couple of days, provided I
don't turn it off at night.

Actually, the time to live value in the returned DNS reply will
limit
any caching. I just did one test for Yahoo and it showed 34
seconds. Another one showed 3 min 2 sec, so upstream caches will
return a varying
TTL depending on when they obtained the record. Those times are
nowhere near "overnight".


I had no idea TTLs were so short these days. When I was admin'ing
DNS 15+ years ago, a week was a very common TTL (time-to-live).

+1.
My Albitz&Liu talks of a default of 85400 seconds, which is 24 hours
which *IS* overnight!

Why should a site have such short TTL?
The only justification I can think of is that they are implementing
Round Robin DNS that way.

And that's a poor justification. Maybe have a look at 'rrset' in the
bind manual.



--
Per Jessen, Zürich (7.2°C)
http://www.hostsuisse.com/ - dedicated server rental in Switzerland.

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