driftfile /var/lib/ntp/drift   
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery
restrict 127.0.0.1
restrict -6 ::1  
restrict 192.168.200.0 mask 255.255.255.0 nomodify notrap
 server ntp1.aliyun.com iburst
 server ntp2.aliyun.com iburst
 server ntp3.aliyun.com iburst
 server ntp4.aliyun.com iburst


server 127.127.1.0 fudge
127.127.1.0 stratum 8