$ORIGIN example.com.     ; designates the start of this zone file in the namespace
$TTL 1h                  ; default expiration time of all resource records without their own TTL value

; if a name ends in a . its a fqdn if not its relative
; name  (ttl) record_class  record_type record_data

example.com.   IN  SOA   ns1.example.com.  (
                              dnsadmin.example.com ; email
                              2020022310            ; serial
                              86400                 ; refresh period - 1d
                              7200                  ; retry period - 2h
                              2419200               ; expire time - 4w
                              1800                  ; minimum ttl - 30m
                      )

example.com.   IN  NS    ns1                      ; ns1.example.com - nameserver for example.com
example.com.   IN  NS    ns2                      ; ns2.example.com - backup nameserver for example.com
example.com.   IN  MX    10 mail.example.com.     ; mail.example.com - mail exchange for example.com
ns1            IN  A     10.2.3.4                 ; IPv4 address for ns1.example.com
ns2            IN  A     10.2.3.5
mail           IN  A     10.2.3.4