PROJECT 4: DNS
===============

                                    1  1  1  1  1  1
      0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                      ID                       |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |        Parameter                              |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                    QDCOUNT                    |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                    ANCOUNT                    |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                    NSCOUNT                    |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                    ARCOUNT                    |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

ID         = monotonically increasing from client to server; copied by server
Parameter  = Bit 0  = 0 from client to server; 1 from server to client
             Bit 1-4 = 0 from client to server; copied by server
             Bit 5   = 1 from server to client
QDCount    = 1 from client; 0 from server
ANCount    = 0 from client; 1 from server
NSCount    = 0 from client; 1 from server
ARCount    = 0 from client; 1 from server

Create client and server that exchange these messages. As given above, the 
field "parameter" has to be modified by the server after receiving the 
message from the client. The server also includes its own IP address after
the header message given above.

    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                    SRV IP ADDR                |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

That is, it adds the 4 byte field to the header above and sends it to the
client. The client needs to print the IP address in dotted decimal notation
after it receives the reply from the server.

Send and receive multiple messages from the client to the server until a
given number of messages have been sent. Accept the number of messages to
be sent as a command line argument in the client.

Group 13 :
Implement as a TCP concurrent server with processes

Group 2 :
Implement as a UDP server with select