1. Install # yum install ntp ntpdate ntp-doc 2. Turn on service # chkconfig ntpd on 3. Sync one time # ntpdate pool.ntp.org 4. Configure ntpd # vi /etc/ntp.conf Add public servers server 0.rhel.pool.ntp.org server 1.rhel.pool.ntp.org server 2.rhel.pool.ntp.org 5. Start the NTP server. The following will continuously adjusts system time from upstream NTP server. No need to run ntpdate: # /etc/init.d/ntpd start