Section 2 of 5
The countdown starts the moment you get the answer
TTL, caching, and what is still being served.
A record leaves its zone with a number attached, and from that moment the zone has no say in what anybody else serves. Three pieces on the mechanism, the negative case, and the migration it governs.
3 pieces in this section
- 01The countdown starts the moment you get the answerTTL is not how long a record is valid — it is how long somebody else may keep serving the old one.
- 02Negative answers are cached tooThe absence of a record is itself an answer with a lifetime, and it is the one people forget.
- 03Lowering the TTL before you move anythingThe standard preparation for a migration, and why it has to happen a day early.