For various purposes (such as the accurate labelling of backup files) it is a good idea if the time on the server is correct. Here is how to set up a server so that it keeps track of the time from an authoritative source on the Internet.
Installing an NTP client
yum install ntp
Telling it where to look for the time
Starting the service
service ntpd start
Telling the service to start automatically
chkconfig ntpd on