Computer networks

Question

Which of the following system calls not used in UDP echo server program?
A) listen()
B) socket()
C) bind ()
D)recvfrom()

Comments

A) LISTEN ???

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TCP echo client :- Socket() -->Connect() and then start sending and receiving messages.

TCP echo server :-Socket()-->>bind()-->>listen()-->>accept() and now after connect() call from client , sending , receiving messages.

UDP echo client :-Socket()-->>bind() and then sending and receiving messages.

UDP echo server :-Socket()-->>bind() and then sending and receiving messages.

http://www.cs.northwestern.edu/~agupta/_projects/networking/TCPClientServer/report.html

Answer 1

The steps of establishing a UDP socket communication on the server side are as follows:

• Create a socket with the socket() function;
• Bind the socket to an address using the bind() function;
• Send and receive data by means of recvfrom() and sendto()

http://www.cs.dartmouth.edu/~campbell/cs60/socketprogramming.html

Comments

what is echo server program(as per the question)?

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An echo server is usually an application which is used to test if the connection between a client and a server is successful. It consists of a server which sends back whatever text the client sent.

Answer 2

Listen is not used in UDP as we donot need any synchronization and  connection establishment in UDP.