ymstudy.cn.		30 IN SOA jm1.dns.com. admin.dns.com. (
				1614931700 ; serial
				7200       ; refresh (2 hours)
				3600       ; retry (1 hour)
				1209600    ; expire (2 weeks)
				1800       ; minimum (30 minutes)
				)

Name servers:
ymstudy.cn.		30 IN NS jm1.dns.com.
ymstudy.cn.		30 IN NS jm2.dns.com.