Understanding TTL and DNS propagation

Propagation is the reason a DNS change isn't instantly visible to everyone, and it's the most common source of confusion.

When you edit a record, our authoritative nameservers update immediately. But resolvers around the world may still be serving a cached copy of the old value until its TTL expires. The TTL — measured in seconds — is set per record and tells resolvers how long they may cache it.

Practical consequences:

• A record with a 3600s (1 hour) TTL can take up to an hour to change everywhere.
• Before a planned migration, lower the TTL (e.g. to 300s) a day ahead. Then when you make the real change, the world picks it up within minutes.
• Your own machine may cache too — test changes with dig name +short or an external propagation checker rather than trusting your browser.

There is no way to force every resolver on earth to drop its cache early; the TTL is the control. Set it thoughtfully and propagation stops being a mystery.