I have a Centos 7 server which has tens of domain names and IPs.
The IP addresses are pointing to my server.
Each domain name is pointing to its own IP via A record.
I want to configure my FQDN in order to install Postfix.
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
hostname -f returns:
domainname returns (none)
Do I have to choose a real domain purchased and prepend to it the hostname like this:
ip hotname.domainame hostname