Migration
DNS cutover checklist for moving a live service
DNS cutover should be one of the last steps in a migration, not the moment the destination is first tested. Prepare the new service until it can handle production, then use DNS to direct users to something that is already working.
Lower the relevant TTL ahead of time
Reduce TTL early enough for resolvers holding the previous high value to expire before the planned change. Record the old value so it can be restored after the migration stabilizes.
Test the destination using the real hostname
Use a hosts-file override, preview feature, or controlled routing method so the destination serves the production hostname and can be tested for TLS, redirects, cookies, virtual-host routing, and application URLs.
Complete final state synchronization before changing the record
Copy data that changed after the initial migration and decide whether a short write freeze is needed. The destination should be as current as the recovery objective requires before new users are sent there.
Monitor both addresses during cache transition
Verify authoritative DNS immediately, then check recursive resolvers, logs, health checks, forms, and application writes. Keep the source available for clients with cached old answers and retain a documented rollback until the transition is complete.