NTP is a protocol developed for synchronize your system date and time over a network, If you could not found that package install in it.

# yum install ntp ntpdate ntp-doc

Once installed ntp package run on your system,
# /etc/init.d/ntpd start

Starting ntpd:                                             [  OK  ]
#  ntpdate

26 Mar 16:20:52 ntpdate[29516]: no servers can be used, exiting

Do you need synchronize your system clocks to an NTP server

immediately,  execute the command,
 
# /usr/sbin/ntpdate pool.ntp.org
 26 Mar 16:24:40 ntpdate[29639]: adjust time server 120.88.46.10 offset -0.001103 sec 
# netstat -anp | grep ntp

udp        0      0 103.235.104.103:123         0.0.0.0:*
                 29821/ntpd
udp        0      0 127.0.0.1:123               0.0.0.0:*
                 29821/ntpd
udp        0      0 0.0.0.0:123                 0.0.0.0:*
                 29821/ntpd
udp        0      0 fe80::216:3eff:fe97:232c:123 :::*
                  29821/ntpd
udp        0      0 ::1:123                     :::*
                 29821/ntpd
udp        0      0 :::123                      :::*
                 29821/ntpd

Do you want to set clock time on boot time, Open a rc.local file and add a line into it.
 
# vim /etc/rc.local
  /usr/sbin/ntpdate  pool.ntp.org 

Once updated on that file the system clocks will be changed on next boot.
 
# init 6