By default, the server access mode is Direct, but it can be changed into Round-Robin. A health-check function is available for operator management, which can optionally be disabled. The health-check polls the server every 30 seconds (configurable) with an improbable username. If the server does not respond to this health-check, it is marked down.
If the first server in the list cannot find a user, the next server in the RADIUS server list is queried, only when access mode is set to Round-Robin. If multiple RADIUS servers are used and access mode is set to Direct, it is assumed they all have the same user database.