Use default server hostname (with SSL encryption)?

Hey community, I’m new to linux and servers in general so hoping for some direction from you guys. There are a couple of things I’d like to know about the hostname and connection to it.

  1. When I set up a clean installation of Ubuntu on my server, I get a default hostname. Can I install QuickBox to use this hostname rather than create a new one?

  2. If I use the default hostname, will the domain have a valid certificate?

Any help greatly appreciated

Domain and hostnames are not related not in the way you are thinking.

yes you can choose to keep the hostname you setup when you install OS.

as i said before they have nothing to do with each other.
valid cert is dependent on the cert and the dns that your domain uses.

as i said before they have nothing to do with each other.
valid cert is dependent on the cert and the dns that your domain uses.

I saw the Let’s Encrypt install guide. Is it possible to retrieve the DNS that my domain uses and create an SSL certificate for it? Or is this beyond the scope of what I can/should do? Excuse my lack of knowledge btw.