Name service scope is an important concept for understanding RBAC. The scope of a role might be limited to an individual host. Alternatively, the scope might include all hosts that are served by a name service such as NIS, NIS+, or LDAP. The name service scope for a system is specified in the file /etc/nsswitch.conf. A lookup stops at the first match. For example, if a rights profile exists in two name service scopes, only the entries in the first name service scope are used. If files is the first match, then the scope of the role is limited to the local host.