Install Chrony and Configure NTP server for time adjustment.
[1] Install Chrony.

[root@localhost ~]# yum -y install chrony
[root@localhost ~]# vi /etc/chrony.conf
# line 3: change servers for synchronization
#server 0.centos.pool.ntp.org iburst
#server 1.centos.pool.ntp.org iburst
#server 2.centos.pool.ntp.org iburst
#server 3.centos.pool.ntp.org iburst
server 2.vn.pool.ntp.org iburst
server 2.asia.pool.ntp.org iburst
server 0.asia.pool.ntp.org iburst
# line 25: add the network range you allow to receive requests
allow 10.0.0.0/24
[root@locahost ~]# systemctl start chronyd
[root@localhost ~]# systemctl enable chronyd

[2] If Firewalld is running, allow NTP service. NTP uses 123/UDP.

[root@localhost ~]# firewall-cmd --add-service=ntp --permanent
success
[root@localhost ~]# firewall-cmd --reload
success

[3] Verify it works normally like follows.

[root@localhost ~]# chronyc sources