SOA MX A CNAME PTR TXT "-spf"
”.” is the root “/” of dns
Some Top Level Domains are .com and .edu
.com.google = google.com
.edu.cun.library = library.csun.edu
The registrar that has authority of the .edu top level domain registers “csun” but not “library”
$ cat zone.txt ~SOA~ example.com. IN A 192.0.2.1 ; IPv4 address for example.com www IN CNAME example.com. ; www.example.com is an alias for example.com