Mailinglist Archive: opensuse (1420 mails)

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Re: [opensuse] optimizing resolv.conf
On 01/03/2014 12:12 PM, Felix Miata wrote:
On 2014-01-03 17:43 (GMT+0100) Per Jessen composed:

An application really should not be caching, it should leave that to
nscd or a caching dns.

Or? I have dnsmasq running. Should I turn off nscd?

It is really de minimis. Even over slow wireless your ping time to a caching
server is on the order of 2/3 millisecond. The cache query time itself is 2-3
milliseconds. Whether you run a nscd or a browsercache, you are only saving at
most a millisecond.

If you have a caching nameserver - there is no need for another cache;

If you don't have a local caching nameserver - then, of course cache on your
local machine. Now there is a HUGE question about how much latency develops in a
"browser cache" as the number of files or cache size grows. That could cause a
"browser cache" to be interjecting additional delay just to read its own cache.
I have not tested, but I doubt the sqlite3 type cache structure of FF compares
to the speed of bind. I suspect a nscd type cache is more efficient than a FF
cache, so you may be better off disabling your browser cache if you have another
local caching service, so long as you can tell your browser to use the external
cache. (that in itself may/may not be possible) As pointed out, a browser cache
does absolutely nothing for all of the remaining apps that need address
resolution.

That is where a standard caching setup such as bind, etc.. can eliminate a lot
of "gee, I wonder" questions regarding this topic. As long as you never see a
"looking up host" message from any of your applications, how you do it is
largely irrelevant. If I'm going to invest the time to setup a caching solution,
I want to insure it is spent on a long term reliable solution.

--
David C. Rankin, J.D.,P.E.
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