TTL stands for time to live. It is the number of seconds that a resolver may keep a DNS answer before asking again.
A TTL of 3600 means one hour. A low TTL means answers expire quickly, and a high one means they are reused for longer.
'Propagation' is not a single event. It is simply the many caches around the world reaching the end of their stored answer at different moments.
After you change a record, caches that stored the old answer can keep it until its TTL ends. Caches that had not stored it see the new record at once.
Some people lower the TTL before a planned change, wait for the old TTL to pass, and raise it again afterwards. That shortens the period in which old and new answers are both in use.
DNS Domain Detective shows your records with their TTL, so you know how long a change may take to show up. Open DNS Domain Detective
DNS Domain Detective is now available on the App Store.
Last reviewed: 2026-11-02
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