How to change the timezone

a. How to change date and time
# date +%D -s YYYY-MM-DD
# date +%T -s HH:MM:SS
or
# system-config-time

b. To change the timezone of your system, edit
# vi /etc/sysconfig/clock
ZONE="America/New_York"

to set US/Eastern time. Upon reboot the system will be set to the defined timezone.

Note: To reflect the change on local machine, you have to to link the zoneinfo file to /etc/localtime.
# ln -sf /usr/share/zoneinfo/America/New_York /etc/localtime
Note: Make sure to set the timezone to right/correct timezone file

c. Verify the change using the date command
# date