Servidores DNS Principal (mname) y Secundario (rname)
host: learningstudio.com
class: IN
ttl: 900
type: SOA
mname: dns-amer-2.ptns.pearson.com
rname: gns-dnsoperations.pearson.com
serial: 65
refresh: 900
retry: 900
expire: 2592000
minimum-ttl: 900