Add certbot -d example.com --manual --preferred-challenges dns certonly to Certbot Commands about documentation HOT 2 CLOSED

There is no need for that since --standalone does what it says. It is a standalone that doesn't require nginx or apache2.

from documentation.

--standalone spins up a temporary web server by certbot and doesn't require installing any yourself, but it still requires port 80 to be exposed for the HTTP challenge. DNS challenge can be useful to document since certbot DNS challenge is easier than acme for most users.

from documentation.