SOCK_DGRAM style is used for sending
individually-addressed packets unreliably.
It is the diametrical opposite of
Each time you write data to a socket of this kind, that data becomes
one packet. Since
SOCK_DGRAM sockets do not have connections,
you must specify the recipient address with each packet.
The only guarantee that the system makes about your requests to
transmit data is that it will try its best to deliver each packet you
send. It may succeed with the sixth packet after failing with the
fourth and fifth packets; the seventh packet may arrive before the
sixth, and may arrive a second time after the sixth.
The typical use for
SOCK_DGRAM is in situations where it is
acceptable to simply re-send a packet if no response is seen in a
reasonable amount of time.
See Datagrams, for detailed information about how to use datagram