Servidores DNS Principal (mname) y Secundario (rname)
host: vps.etecsa.cu
class: IN
ttl: 300
type: SOA
mname: ns0.cd.etecsa.cu
rname: postmaster.etecsa.cu
serial: 2020102826
refresh: 300
retry: 60
expire: 600
minimum-ttl: 300