What is a FQDN?
I understand FDQN stands for a "Fully Qualified Domain Name" but what exactly is this?
An (FQDN) - fully qualified domain name, consists of a host and domain name, including top-level domain.
www.gordano.com is a fully qualified domain name.
www is the host, gordano is the second-level domain, and .com is the top level domain.
A FQDN always starts with a host name and continues all the way up to the top-level domain name, so www.test.gordano.com would be classed as a FQDN if it existed.