Quindi per BIND9 io riassumerei cosi' il file di configurazione /var/lib/bind/mysipdomain.com.hosts:
$ttl 38400
mysipdomain.com. IN SOA ns1.mysipdomain.com. miamail.yahoo.com. (
2011120212
10800
3600
604800
38400 )
mysipdomain.com. IN NS ns1.mysipdomain.com.
mysipdomain.com. IN NS ns2.nselsewhere.com.
mysipdomain.com. IN A xxx.xxx.xxx.xxx
mysipdomain.com. IN MX 10 mail.mysipdomain.com.
mail.mysipdomain.com. IN A xxx.xxx.xxx.xxx
ns1.mysipdomain.com. IN A xxx.xxx.xxx.xxx
main.mysipdomain.com. IN A xxx.xxx.xxx.xxx
secondary.mysipdomain.com. IN A xxx.xxx.xxx.xxx
backup.mysipdomain.com. IN A xxx.xxx.xxx.xxx
_sip._udp.mysipdomain.com. 8640 IN SRV 0 1 5060 main.mysipdomain.com.
_sip._udp.mysipdomain.com. 8640 IN SRV 0 3 5060 secondary.mysipdomain.com.
_sip._udp.mysipdomain.com. 8640 IN SRV 1 0 5060 backup.mysipdomain.com.