Switching host or DNS provider without downtime: the checklist

Updated 23 September 2026

A poorly prepared migration means a site that cannot be reached for hours and lost email. Well prepared, nobody notices. Everything happens in the days before the switch.

Understand TTL first

Every DNS record has a TTL (time to live): how long, in seconds, resolvers keep it in cache. With a TTL of 86,400, a change can take up to 24 hours to be seen by everyone. With a TTL of 300, five minutes are enough.

D-2: lower the TTL

At least 24 to 48 hours before the switch, lower the TTL of the records you will change (A, AAAA, CNAME, MX) to 300 seconds. You have to wait for the old TTL to expire before the new one is known everywhere.

D-1: inventory and prepare

Export the current DNS zone or note every record: A, AAAA, CNAME, MX, TXT (SPF, DKIM, DMARC, Google or Microsoft verifications), SRV, CAA.
Recreate them identically at the new provider, including subdomains.
Prepare the new server: site copied, database imported, HTTPS certificate ready.
Test the new server before switching, by forcing your computer to use it through the hosts file.

D-day: switch over

Changing host only: point the A, AAAA or CNAME records to the new server. Thanks to the short TTL, the switch is almost instant.
Changing DNS provider: change the name servers (NS) at the registrar. Beware: the NS TTL is set by the domain's registry and is often 48 hours. Both providers must therefore serve an identical zone during that time.

Follow the rollout with our DNS propagation tool: it queries resolvers in several regions of the world.

The two traps that break everything

DNSSEC

If DNSSEC is active, the registrar publishes a DS record tied to the old provider's keys. Changing name servers without dealing with it makes the domain unreachable for resolvers that validate DNSSEC. The simple fix: turn off DNSSEC and remove the DS, wait 48 hours, migrate, then turn DNSSEC back on at the new provider.

Email

If the MX records change, some email may land on the old server during propagation. Keep the old mailbox active for a few days and check it. If email is not moving, make sure the MX and TXT records are identical at the new provider.

After the switch

Keep the old server running for 48 to 72 hours, until every cache has expired.
Check the site, the HTTPS certificate, sending and receiving email, and forms.
Raise the TTL back to a normal value, for example 3,600 seconds, once everything is stable.
Cancel the old hosting only after a week without problems.

Open the NetCheck tools

Frequently asked questions

How long does DNS propagation take?

It depends on the TTL of the old record: a few minutes if it was lowered in advance, up to 24 or 48 hours otherwise. A name server change can take up to 48 hours.

Why do some people see the new site and others the old one?

Each resolver keeps the old answer until its cache expires. During that time both versions coexist, which is why the old server must stay online.

Do I need to transfer the domain to change host?

No. The domain can stay with its registrar: you only need to change the DNS records or name servers to point to the new host.