Server setting
After installing CentOS7, small settings are necessary.
NTP client
Install chrony (an NTP client) by yum.
[root@server ~]# yum -y install chrony Loaded plugins: (snipped...) Installed: chrony.x86_64 0:3.4-1.el7 Dependency Installed: libseccomp.x86_64 0:2.3.1-4.el7 Complete!
Set NTP servers in /etc/chrony.conf