Servidores DNS Principal (mname) y Secundario (rname)
host: tjudb.cn
class: IN
ttl: 180
type: SOA
mname: f1g1ns1.dnspod.net
rname: freednsadmin.dnspod.com
serial: 1572790885
refresh: 3600
retry: 180
expire: 1209600
minimum-ttl: 180