Broadcasts

Most connectionless transport protocols support broadcast in the same fashion, where any bound socket can send a broadcast if the SO_BROADCAST option is set, and broadcasts sent to the appropriate local endpoint are received without any additional work on the part of the application. NetBIOS transports, however, handle broadcasts somewhat differently. In order to receive broadcasts, an application must bind to the NetBIOS broadcast address, which is an asterisk (*) followed by 15 spaces (ASCII character 0x20). This means two things: a socket must be specially bound to receive broadcasts, and applications can't depend on receiving broadcasts intended only for a specific application, since all NetBIOS broadcasts are delivered to this address. In other protocols such as UDP/IP and IPX, broadcasts are delivered to a socket only if the broadcast was sent to the same port to which the socket was bound.