Registro DMARC
v=DMARC1;p=reject;rua=mailto:dmarc_rua@emaildefense.proofpoint.com;ruf=mailto:dmarc_ruf@emaildefense.proofpoint.com;fo=0

Servidores DNS Principal (mname) y Secundario (rname)
host: mytricaredental.net
class: IN
ttl: 3600
type: SOA
mname: ns3.level3.net
rname: root.bcbssc.com
serial: 7
refresh: 10800
retry: 3600
expire: 2419200
minimum-ttl: 900