This is an area I am still learning about. However there are some things I have fathomed. It is worth noting that Red Hat 6 seems to use chkconfig and Red Hat 7 uses systemd. In summary chkconfig works with bash scripts and systemd with service units, the future is systemd, without doubt. See 10.2. Managing System Services - Red Hat Customer Portal for some details on this, however we often end up with older versions, so this is all good to know.
If you type chkconfig --list you will see a complete list of services. If you read Chapter 12. Services and Daemons - Red Hat Customer Portal you will see this is how you manage the rc directories in /etc
A good reference is Chapter 10. Managing Services with systemd - Red Hat Customer Portal but also see systemd.