FQDN on Ubuntu 20.04lts

[techlists at phpcoderusa.com]

Hi,

I recently installed Ubuntu 20.04 and it did not ask for my domain.  I 
am building a PHP web hosting server for learning.

Prior to this when installing Linux it always asked me for the domain 
the machine was going to be in.  Maybe I missed something.

When I issued the command "hostname" it returned the host name.  When I 
issued the command "hostname -f" it only returned the hostname.

To fix this I added this line to /etc/hosts "255.255.255.255  
hostname.Domain.tld hostname".

255.255.255.255 represents my public IP.

Questions

1) Did I miss something on the install?
2) I am running BIND so is the line I added necessary to "fix" the FQDN?
3) Is there another or better way?
4) Since my webserver is on a private IP using port forwarding, should I 
use my private IP in /etc/hosts instead of my public IP?


Thanks!!