How to change DNS records without downtime

1. Lower the TTL a day ahead

Find the current TTL of the records you will change (for example A and MX) with the propagation checker. Set it to 300 seconds at least one old TTL before the switch, usually a day ahead. Resolvers then cache the record for only 5 minutes.

2. Prepare the new host first

Copy the website and test it on the new server, and set up mailboxes before you switch. Keep the old host running until the change has fully propagated, so visitors who still reach it get a working site.

3. Change the records

Update the A, AAAA or CNAME records for the site, or the MX, SPF and DKIM records for email. If your SPF record names the old provider, update it at the same time, or mail from the new one may land in spam.

4. Watch propagation

Enter the new IP or host as the expected value and turn on automatic re-checks. When every resolver shows a green match, nearly all visitors reach the new host. Test email in both directions.

5. Raise the TTL again

Once everything works, set the TTL back to 3600 or more. Longer TTLs mean fewer lookups and faster page loads, and they protect you if your DNS provider has a short outage.

Checklist

Before you switch:

• TTL lowered to 300 at least a day before.
• New host tested and email accounts created.
• SPF, DKIM and DMARC updated for the new mail provider.
• Old host kept running until all resolvers show the new value.
• TTL raised back once the move is complete.