Ofc you have to add domain name in you HTTP service configuration if you want people be able to open your site on your domain name.
And not necessary to alias, because it depending on configuration that men, who doing config, have.
If site already exists and you want to add another name to it, so ofc you need to add alias. If site don`t exists yet so you need to add name and not alias.
This info exists and avail in the HTTP service documentation.