With the popularity of cluster systems, time synchronization between systems has become a major problem. Some systems do not want to connect to the external network. The need to build an internal network time synchronization server is here
Install NTP server
#apt install -y ntp
# dpkg --get-selections ntp [Can be used to confirm NTP is installed]
# dpkg -s ntp [Can also be used to confirm NTP is installed]Configure NTP server
#vim /etc/ntp.conf
...
pool ntp7.aliyun.com iburst //阿里云
pool cn.ntp.org.cn iburst //中国
pool edu.ntp.org.cn iburst //中国教育网
pool hk.ntp.org.cn iburst //中国香港
pool jp.ntp.org.cn iburst //日本
...Restart NTP
#systemctl restart ntp
Done~