I've been reading the guides on linode about setting up a server to host websites. One concept that bothers me most is FQDN. From what I've read, FQDN is very important and it MUST be set. In my actual case, I've been running 2 linode servers for years, for one of them I just set it with my name
220.127.116.11 shenkwen shenkwen
for the other I leave it as the default
127.0.1.1 ubuntu.members.linode.com ubuntu
For these 2 servers, I've never encountered any problem regarding not properly setting FQDN. So I don't understand why setting a FQDN is important and when I am going to regret that I didn't set one properly.
Also I am reading this guide on github, it says
Hostnames are also important because they form part of a computer's Fully Qualified Domain Name (FQDN). Assigning a FQDN to a computer makes it reachable via the public Domain Name System (DNS), i.e. the Internet.
I am really confused by why the computer is reachable by just setting a FQDN. I mean I can set FQDN to anything, for example
stackoverflow.com, but how can internet reach to my computer by this "FQDN"?