The linux command "rdate" is very useful to quickly sync your server time clock with an NTP (Network Time Protocol) Server.
There are a few options: rdate [-p] [-s] [-u] [-l] [-t sec] [host...]
-p : Print the time returned by the remote machine.
-s : Set the system time to the returned time.
-u : Use UDP instead of TCP as the transport.
-l : Use syslog to output errors (cron.warning) and output (cron.info)
-t : Set timeout in seconds for every attempt to retrieve date.
Step 1: Make sure you have rdate and cron installed
yum install rdate vixie-cron
Step 2: Pick a server to use to sync time with.
List of HOSTNAME's: http://tycho.usno.navy.mil/ntp.html
Step 3: Edit your cron and add a schedule to run the command as often as needed within reason.
(Generally once a day is acceptable)
Add the following to your cron: replace the HOSTNAME with one from the list above
0 6 * * * /usr/bin/rdate -s HOSTNAME 2>&1 >> /dev/null
NOTE: 0 6 * * * means: Check once at 6:00 AM every day