Servidores DNS Principal (mname) y Secundario (rname)
host: dns558.com
class: IN
ttl: 3600
type: SOA
mname: 
rname: hostmaster.nameserver
serial: 456
refresh: 28800
retry: 7200
expire: 604800
minimum-ttl: 5

Servidor de Correo
host: dns558.com
class: IN
ttl: 3600
type: MX
pri: 10
target: mail.dns558.com