aff.edu.vn.		30 IN SOA ns1.zonedns.vn. root.aff.edu.vn. (
				2023041304 ; serial
				1200       ; refresh (20 minutes)
				600        ; retry (10 minutes)
				1209600    ; expire (2 weeks)
				3600       ; minimum (1 hour)
				)

Name servers:
aff.edu.vn.		30 IN NS ns4.zonedns.vn.
aff.edu.vn.		30 IN NS ns1.zonedns.vn.
aff.edu.vn.		30 IN NS ns2.zonedns.vn.
aff.edu.vn.		30 IN NS ns3.zonedns.vn.