The dependency relationship between a parent and a child is called a link. The link is characterized by the dependency category, the location of the service groups, and the rigidity of dependency.
A dependency may be online, or offline.
A dependency may be local, global, remote, or site.
A dependency may be soft, firm, or hard with respect to the rigidity of the constraints between parent and child service group.
You can customize the behavior of service groups by choosing the right combination of the dependency category, location, and rigidity