1. An access control system for controlling access to management objects in a distributed network, comprising: an access control database, including access control objects, the access control objects including: group objects, each defining a group and a set of users who are members of the group; and rule objects, a subset of the rule objects each specifying: a set of the group objects, a set of the management objects, and access rights by the users who are members of the groups defined by the specified set of the group objects to the specified set of management objects; and a plurality of access control servers, each access control server controlling access to a distinct subset of the management objects in accordance with the access rights specified in the access control database; wherein at least one of the access control servers receives access requests from the users and distributes the received access requests among the access control servers for processing; a subset of the access requests specifying operations to be performed on specified sets of the management objects; wherein each access request in the subset is sent for processing to one or more of the access control servers in accordance with the management objects to which access is being requested by the access request; the access control servers responding to the access requests from the users by granting, denying and partially granting and partially denying the access requested in each access request in accordance with the access rights specified in the access control database.