How do I move hosts without downtime?

Reduce the TTL on the records you will change to a few minutes, and do it at least one full previous-TTL period before the move.

This is the only step that cannot be done later. Copies already cached expire on the old value regardless of what you publish afterwards.

Leave everything else alone. Lowering the TTL is not itself a change of destination and causes no visible effect.

Note the previous TTL value, because it tells you how long you must keep the old host running after the switch.

Serve the real site at the new host, reachable by a temporary hostname or by editing your own hosts file so you can test it under the real name.

Issue the certificate for the production hostname at the new host before the switch. A destination without a valid certificate produces a full-page warning rather than a slow page.

Test all four host and scheme combinations at the new destination, and confirm the redirect behaviour matches the old host's.

Verify the application works, not just the home page: forms, logins, uploads, scheduled jobs and anything that talks to a database.

Confirm the new host is not rate-limiting or bot-filtering in a way the old one did not, which is a common source of post-move crawl problems.

Change the address record and verify it immediately at your authoritative nameserver, which proves it was published.

Watch public resolvers converge over the next few minutes, which is what the lowered TTL bought you.

Do not change anything else at the same time. A host move combined with a URL structure change makes every subsequent problem ambiguous.

Keep the mail records untouched unless mail is also moving, and verify them afterwards regardless.

Leave the old host serving for at least the previous TTL, and comfortably longer. Clients holding a cached answer cannot be reached by anything you publish.

Watch the old host's access logs. Traffic falling to near zero is the signal that the transition has completed.

Keep the data in sync while both are live, or put the old host into a read-only mode, so a visitor landing on the old one does not write data that will be lost.

Restore the TTL to its normal value once traffic has moved, so you are not paying for query volume you do not need.

Compare the site at the new host against the old one page by page for the templates that matter, rather than trusting the home page.

VeriFixScan reports `dns.resolution` and `infrastructure.ip_dns_consistency` for where the name now points, and `transport.certificate_details` and `transport.certificate_coverage` for whether the certificate at the destination is valid and covers the name.

`availability.status_classification` and `availability.broken_links` confirm the site answers and that no section started returning errors at the new host.

Re-check mail records after the move even if you did not touch them, because zone edits are easy to make more broadly than intended.