[Unbound-users] RR ttl in dump_cache
wouter at NLnetLabs.nl
Tue Jul 7 14:50:22 UTC 2009
-----BEGIN PGP SIGNED MESSAGE-----
On 07/07/2009 04:05 PM, Michael Tokarev wrote:
> I noticed the (relatively) new dump_cache/load_cache
> commands of unbound-control, and started experimenting.
> And immediately come across an.. issue. The TTL for
> each RR is expressed as time-to-live since "now", it
> is not an expiration time. For this reason it's not
> possible to save the cache and load it back on restart
> for example, because ttl in that case will be invalid.
Yes at the same time the problem but also the reason
people do it.
> I wonder if it's a good idea to use absolute expire
> time in place of TTL in dump/load_cache format. If
> nothing else, prefixing the field with an equal sign
> will do the trick (=1234567 to mean absolute time,
> 1234567 - current - to mean ttl as it is now).
> And in general, do people use dump/load_cache to
> start with?
Well they want to dump to examine contents.
Want to load to 'hot-start' the cache. So that the
resolver starts with a full cache. For that to work
the TTLs have to make the data 'valid'.
I guess that the time of the dump could be stored.
And the readback could make items that used to be valid,
but are now expired, have a TTL of 10-30 seconds (random)
spreading the work to refresh the entries.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.9 (GNU/Linux)
Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/
-----END PGP SIGNATURE-----
More information about the Unbound-users