SECURING
To prepare a Domino server to request certificates from the Let's Encrypt CA, follow the procedure that corresponds to the type of challenge to use, either HTTP-01 or DNS-01. HTTP-01 is the challenge most typically used.
Preparing to request certificates using DNS-01 challenges Before you can request a certificate from the Let's Encrypt CA using DNS-01 challenges, you first need to create a DNS Provider Configuration and a DNS Provider Account.