DNS records

When try to reach "athome.tld", your device ask a DNS resolver what IP is behind. DNS is like road signs.

To create this sign, you must link the domain name to your IP in a zone. It can be done in registrar panel if you don't host your own domain name server (see nsd later 😉). As example :

athome.tld    A    192.0.2.2

Different records exists. You must at least know:

blog.athome.tld CNAME athome.tld
wiki.athome.tld CNAME athome.tld
webmail.athome.tld CNAME athome.tld

Learn more with these links :

https://en.wikipedia.org/wiki/Domain_Name_System
https://howdns.works/
Learn how to host a domain name server.