If you need to configure services in your linux system you can use a simple command chkconfig.
List all services and their status and whether they are stopped or started in each runlevel.
This option adds a ntpd service for management
#chkconfig --add ntpd
The service is removed from chkconfig management
#chkconfig --del ntpd
Enable ntpd service to start on level 3.
#chkconfig --level 3 ntpd on
Disable ntpd service to start on level 4.
#chkconfig --level 4 ntpd off