Security

Is there a document explaining what factors an aruba controller uses to send radius request to the next radius server down  in the group for failover ?

e.g does it ping or use some radius method of determining wheter the radius service is responding on the radius server ?

In each radius server there is a definition that says how many times the controller will try the radius server  (retransmits 3) and how often if there is no response (Timeout 5 seconds).  When that is exhausted, the radius server is put out of service and the next radius server tried in the server group.  If there is only one server in the server group, it is never put out of service.