A system and method is provided for simulating computer network devices. The method executes a user interface which presents a scenario which includes tasks a user is to perform by interacting with one or more simulated network devices. A network diagram having icons displays a network topology. By selecting an icon a simulated network device is executed and a communication interface to the simulated network device is opened. Commands to the simulated network device issued through the communication interface are interpreted and responded to in substantially the same manner as a corresponding actual network device. In addition, for each simulated network router a routing table is generated and maintained to allow the simulated network devices to respond to commands as realistically as possible. Tasks completed by a user are monitored and evaluated to determine whether the user successfully completed the required tasks.