Do applications need to exchange udp control messages before exchanging data

The answer is NO.

Thats what makes UDP connectionless. Aclient that is going to send a UDP message to the server just sends it.The server does not know it is coming untill it arrives .When a server recieves a UDP message it gets the source address/port and the data.

a1.) template

b2.) master page

answeruse the nslookup utility;