5. Defines

INADDR_ANY

0x00000000 (0.0.0.0)
used for listening on all network interfaces.

INADDR_NONE

0xFFFFFFFF (255.255.255.255)
which has limited applications.

INADDR_BROADCAST

0xFFFFFFFF (255.255.255.255)
used as destination when sending a message to all clients on a subnet that allows broadcasts.

SDLNET_MAX_UDPCHANNELS

32
The maximum number of channels on a UDP socket.

SDLNET_MAX_UDPADDRESSES

4
The maximum number of addresses bound to a single UDP socket channel