Setting the FQDN on Ubuntu 20.04lts

[techlists at phpcoderusa.com]

Hi,

My server is a PHP web server + BIND9 + Postfix + Dovecot.  It is on a 
private network using port forwarding.

There seems to be a lot of advice on the Internet...

The only solution that works for me is to add a line like this one: 
"192.168.10.104 hostname.example.tld hostname" to /etc/hosts.

I used the IP of the server not the public IP that hits my router.

Does this sound right?

Thanks!!