Question

1a)For a client/server application using TCP on Layer-4, which program starts first: Client or Server or both at the same time? Explain why.

b) For a client/server application using UDP on Layer-4, which program starts first: Client or Server or both at the same time? Explain why.

2) Consider an HTTP client that wants to retrieve a web document at a given URL. The IP address of the HTTP server is initially unknown. Which protocols besides HTTP are needed for this communication ?

Answer 1

1)

a)In a client/Server application using TCP on layer-4, Server program starts first ,because server sends a request for a client for connection. From this , we can say that , client program will not start untill server sends request.

b)In a client/Server application using UDP on layer-4, a simple UDP client program starts first ,because client sends a request for a server to accept message(datagram). From this , we can say that , server program will not send its datagram untill client sends request.

2)Other than HTTP , FTP protocols are mostly used along with HTTP because FTP's allow multiple requests to process untill the connection is closed ,whereas,HTTP's allow only a single process at a time.

Telnet is also used other than FTP and HTTP.