Basically, naked/apex domains generally require an A RECORD pointing to an IP address. Heroku prefers you didn't use A RECORDS at all because the IP addresses

Basically, naked/apex domains generally require an A RECORD pointing to an IP address. Heroku prefers you didn't use A RECORDS at all because the IP addresses in their underlying architecture might change. [1] [1] https://devcenter.heroku.com/articles/apex-domains https://devcenter.heroku.com/articles/apex-domains