Resolution:
No. The default protocols are local and tcp under Unix, and tcp under Windows.  To use the udp_broadcast protocol you must specifically list it in the conn_names option of the rtserver.cm file:
NOTE: Udp_boadcast is only used to discover other RTservers, it is not used for any message passing.

setopt conn_names tcp:_node:5101,udp_broadcast

The following (I)nformational messages will be displayed in the RTserver trace file after launch.

{SRV.ICM._node_name_PID} TAL-SS-10026-I Creating conn &ltudp_broadcast> to listen for connections.
{SRV.ICM._node_name:PID} TAL-SS-10022-I Conn &ltudp_broadcast> expands to &ltudp_broadcast:node_name:PORT_ID>.