https://arstechnica.com/gadgets/2020/08/understanding-dns-anatomy-of-a-bind-zone-file/

If you want to be a sysadmin or network administrator of any kind, there's a fundamental technology you really need to understand—DNS, the Domain Name Service. There was a time when a sysadmin with no aspirations to managing Internet-accessible services might have gotten by without understanding DNS, but that time is long, long gone.

You can't learn everything there is to know about DNS in a single article. But that's not what we're looking to do today; instead, we want to give you a clear, concise guide to the structure and meaning of the most important part of the Domain Name System: a zone file, as seen in BIND, the Berkeley Internet Name Daemon.