A number uniquely identifying each conceptual row in the
etsysRadiusAuthServerTable. This value also indicates the
relative priority of the servers. The initial authentication
attempt will be against the server with the lowest value of
etsysRadiusAuthServerIndex and any successive attempt will
be with the next higher value, and so on.
Maintaining the value of etsysRadiusAuthServerIndex for all
active(1) entries across agent reboots is REQUIRED.