Servidores DNS Principal (mname) y Secundario (rname)
host: sundaylessons.org
class: IN
ttl: 3600
type: SOA
mname: ns21.domaincontrol.com
rname: dns.jomax.net
serial: 2021021203
refresh: 28800
retry: 7200
expire: 604800
minimum-ttl: 600