$ORIGIN .
$TTL 3600       ; 1 hour
acme.example.com     IN SOA  ns1.example.com. admin.example.com. (
                                2023040100 ; serial
                                3600       ; refresh (1 hour)
                                3600       ; retry (1 hour)
                                86400      ; expire (1 day)
                                3600       ; minimum (1 hour)
                                )
                        NS      ns1.example.com.
                        NS      ns2.example.com.
                        MX      0 .
                        TXT     "v=spf1 -all"
                        CAA     0 issue "letsencrypt.org"
                        CAA     0 issuewild "letsencrypt.org"