NTP stands for Network Time Protocol, and it is an Internet protocol used to synchronize the clocks of computers to some time reference.
Type the following command to install NTP.
# yum install ntp
Setup the time sync.
# echo 0.centos.pool.ntp.org > /etc/ntp/step-tickers
Set the run levels required for the ntpd service.
# chkconfig --level 345 ntpd on
Start the NTP service.
# service ntpd start
Once the clock is synchronized for the first time, run the following command to set the Hardware Clock to the current System Time.
# hwclock -w
Use either of the following commands verify if the NTP process is running:
# ps aux | grep ntpd
# pgrep -l ntpd
# pgrep -l ntpd
Description of the above commands:
ps – displays information about a selection of the active processes.
pgrep – looks through the currently running processes and lists the process IDs which matches the selection criteria to stdout.