refresh / expire

[Barry Margolin]

In article <a8t361$pmu at pub3.rc.vix.com>, bert hubert  <ahu at ds9a.nl> wrote:
>I was wondering, is there any valid reason for 'expire'? I've been bitten a
>few times by secondaries dropping a zone during prolonged outages. I'm not
>sure why I would ever want that to happen.

Suppose you change secondary DNS providers, and use allow-transfer so that
only the new slave servers can perform zone transfers, but the old provider
never removes the domain from their configuration.  Their customers will
still see the old version of the zone (if this provider also uses the same
servers for authoritative and recursive DNS, as is a common, but
non-recommended, practice among small ISPs).  The expire time ensures that
they will eventually discard their data.

-- 
Barry Margolin, barmar at genuity.net
Genuity, Woburn, MA
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