The UDP module must be able to determine the source and destination internet addresses and the protocol field from the internet header. One possible UDP/IP interface would return the whole internet datagram including all of the internet header in response to a receive operation. Such an interface would also allow the UDP to pass a full internet datagram complete with header to the IP to send. The IP would verify certain fields for consistency and compute the internet header checksum.
The major uses of this protocol is the Internet Name Server , and the Trivial File Transfer .
This is protocol 17 (21 octal) when used in the Internet Protocol. Other protocol numbers are listed in .
 Postel, J., "Internet Protocol," RFC 760, USC/Information
Sciences Institute, January 1980.
 Postel, J., "Transmission Control Protocol," RFC 761,
USC/Information Sciences Institute, January 1980.
 Postel, J., "Internet Name Server," USC/Information Sciences
Institute, IEN 116, August 1979.
 Sollins, K., "The TFTP Protocol," Massachusetts Institute of
Technology, IEN 133, January 1980.
 Postel, J., "Assigned Numbers," USC/Information Sciences
Institute, RFC 762, January 1980.