Install ntpd
yum install ntpd
Stop server
service ntpd stop
Update server
ntpdate us.pool.ntp.org
Sync hardware clock
hwclock -systohc
Check localtime
more /etc/localtime
Replace localtime with correct location
mv /etc/localtime /etc/localtime.bak
ln -s /usr/share/zoneinfo/GB /etc/localtime
Restart ntpd
service ntpd start
$ tzselect