Servidores DNS Principal (mname) y Secundario (rname)
host: es-bbva-cliente.com
class: IN
ttl: 1800
type: SOA
mname: adel.ns.cloudflare.com
rname: dns.cloudflare.com
serial: 2372390082
refresh: 10000
retry: 2400
expire: 604800
minimum-ttl: 1800