[dns-operations] DNS prefetching, DLV and cheap NAT router state table overflow

James Cloos cloos at jhcloos.com
Thu Sep 30 17:34:02 UTC 2010

>>>>> "FW" == Florian Weimer <fw at deneb.enyo.de> writes:

FW> I've noticed that some time after switching on my home workstation
FW> and doing a bit web browsing, DNS resolution ceases to work for a
FW> minute or two.  Unbound (which runs locally and starts from a cold
FW> cache) shows a growing request list during that time.

One thing which helps is to set unbound's timeout to something
reasonable for an edge lan.  (The default of .2 s is too short.)

Start with at least 5s:

	jostle-timeout: 5000

That will keep unbound from flooding most of the time.

If you do not use a traffic shaper on your pipe, you may need a longer
timeout.  If you are ever behind a WWAN or a dialup, 30000 ms seems to
work OK, most of the time.

I'd suggest fixing the init scripts to save unbound's cache when
stopping it and reload the last cache when starting, but I've been
unable to convince unbound to load a cachefile it generated.....

James Cloos <cloos at jhcloos.com>         OpenPGP: 1024D/ED7DAEA6

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