Apparatus for communicating with agent applications. A first request is sent by a server application on a server computer system to a first agent application to communicate with the server application. The first agent application is located in a first network. If the first agent application fails to respond to the first request, a second request is sent by the server application to a second agent application to instruct the first agent application to communicate with the server application. The first agent application is located on a first client computer system that is in a zone with a second client computer system on which the second agent application is located.