A short preparation routine.
ESTABLISH WHERE DNS LIVES
WHOIS for the nameservers. Changes must be made there.
RECORD THE CURRENT STATE
Export the zone, or note every record.
If something breaks, you need to know what it was.
LOWER THE TTL
On the records you will change, a day in advance.
KNOW WHAT MUST NOT CHANGE
Mail records, if mail is staying where it is Verification records Subdomains pointing elsewhere
PLAN THE TESTING
What you will check afterwards: site, mail both directions, subdomains, anything relying on a TXT record.
CHOOSE THE TIMING
A quiet period, and when you are available to fix problems.
Not before a weekend away.
TELL ANYONE AFFECTED
If clients or colleagues depend on the site or mail, warn them.
THE TWO MINUTES THAT MATTER MOST
Recording the current zone, and knowing which provider holds it.
Almost every difficult DNS situation is difficult because one of those was not done.
