1. A method for determining a contact status in a computer network using a network management system, the computer network including a plurality of interconnected network entities including communicating network entities and at least one non-communicating network entity, the network management system executing the steps of: maintaining a virtual network of models of the network entities and model relations representing relations between the network entities, each model including a number of attributes and one or more inference handlers, the attributes being data which define the characteristics of the network entity being modeled, and the inference handler preforming a process on the data upon the occurrence of predetermined events in the model which trigger the inference handler, the attributes including a contact status for the corresponding network entity; communicating with the communicating network entities to obtain operational information as to the status of the communicating network entities and updating the corresponding contact status attributes in the corresponding models; and the inference handlers using the operational information as to the communicating network entities and the model relations between the non-communicating network entities and the communicating network entities to infer the contact status of the non-communicating network entity and updating its contact status, said non-communicating network entity being incapable of communicating with the network management system.