What various services ask for.
SEARCH CONSOLE
A TXT record at the bare domain, or a file on the site.
The TXT method verifies the whole domain including subdomains.
BUSINESS PROFILE
Usually verified by post or phone, sometimes by a TXT record.
EMAIL SENDING SERVICES
A TXT record adding their mechanism to your SPF A TXT or CNAME record for DKIM Sometimes a CNAME for tracking links
PAYMENT GATEWAYS
Occasionally a TXT record for verification.
COLLABORATION PLATFORMS
MX records, several TXT records, and sometimes SRV records.
Follow their instructions exactly; these setups are unforgiving.
MONITORING AND SECURITY SERVICES
Usually a CNAME pointing a subdomain at them.
WHAT THEY ALL HAVE IN COMMON
The record must be added where your DNS actually lives.
And left in place afterwards, because many re-check periodically.
THE COMMON FAILURE
Verification succeeding, the record later removed during a migration, and verification lapsing silently weeks afterwards.
