minimum expire time

John Gilmore gnu at toad.com
Tue Sep 14 23:27:35 UTC 1999


> if it were called minimum-ttl rather than min-expire-time, and if there
> were documentation patches, then i would include it in the distribution.

Hmm, this seems like a bad idea to me.  The reason you can turn down
TTLs is so you can change the records quickly.  If bozos who don't
know what they are doing make their sites "efficient" by setting
artificial minima on TTLs, parts of the Internet will constantly be
dropping out of their sight because they'll be using old records
to access 'em.

Today the advice for someone who's changing their IP address is:

  (1) Turn your TTLs down to a few minutes, a week or two before the change
  (2) Let all the caches empty of the previous long TTLs
  (3) Change your A record when the system address changes.
  (4) Your system is accessible to the net within minutes at its new address.
  (4) When you're sure the change is permanent (perhaps immediately),
      raise your TTLs back to normal (e.g. a week).

If it becomes popular to override low TTLs at cacheing sites, this strategy
won't work, and there will simply be NO way to change IP addresses without
a prolonged service disruption.  That would be far worse than having
dialup customers send a few extra packets to sites that incompetently
set permanent low TTLs.

	John


More information about the bind-workers mailing list