A FQDN (fully qualified domain name) includes a hostname, domain, and top-level domain, example: myhostname.example.com
my server not on domain its local machine on VM.
Then you can use a pseudo (fake) top-level domain that is not used on the Internet, example: myhostname.home.local or myhostname.test.internal
Place your FQDN in /etc/hosts, that file should already include localhost.
replace a.b.c.d with your actual IP address
a.b.c.d myhostname.home.local myhostname