Indicates the current keep-alive status of the RADIUS server.
other : none of the following.
init : the server is in init state.
active : the server is in active state.
checkup: the server is in checkup state.
dead : the server is in dead state.
This object is only instantiated when the corresponding
instance value of crRadiusServerRowStatus is 'active' and
the object value of crRadiusKeepAliveEnabled is 'true'.