Servidores DNS Principal (mname) y Secundario (rname)
host: us-west-2.compute.amazonaws.com
class: IN
ttl: 900
type: SOA
mname: dns-external-master.amazon.com
rname: root.amazon.com
serial: 122439
refresh: 600
retry: 120
expire: 604800
minimum-ttl: 900