To access any of the RAS REST resources, the user executing a request must have sufficient rights to access a particular resource. These are basically the same rights a RAS administrator has in the Parallels RAS Console. For example, a root administrator can access any of the RAS REST resources. On the other hand, a power administrator who doesn't have rights to modify Site settings (as an example) will not be able to access a corresponding REST resource. Similarly, a custom administrator who, for instance, only has rights to view and modify RD Session Hosts will be able to access just that particular REST resource and no other.