The JavaTest Agent can run in active or passive mode:
Active Active agents initiate connections to the JavaTest harness as available. Active agents allow you to run tests in parallel using many agents at once. Active agents allow you to specify the test machines at the time you run the tests.
Passive The JavaTest harness must initiate a connection to each passive agent as needed. Passive agents are simpler, but less flexible because they require that you specify the test machine as part of the test configuration, not at the time you run the tests.

Active agents are recommended unless security restrictions on your platform require that you use passives agents.

For more information about JavaTest Agent, refer to the JavaTest User's Guide or to the JavaTest online help.