its helpful sometimes to synchronize your server with the Network Time Protocol or NTP server to keep track of time automatically. do to that just do these commands in the linux shell prompt..
INSTALL NTP WITH YUM
yum install ntp
MAKE NPT START ON EVERYTIME YOUR COMPUTER BOOTS UP
chkconfig --levels 235 ntpd on
SYCHRONIZE WITH NTP.ORG SERVER
ntpdate 0.pool.ntp.org
START THE NTP DEAMON
/etc/init.d/ntpd start