Mailinglist Archive: opensuse (1420 mails)

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Re: [opensuse] optimizing resolv.conf
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). If the
majority are down in the minutes area now, it is even more important
to have a busy DNS server in your query forwarding logic somewhere.
My ISP is huge, so I just use theirs.

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