Problem
(a) Name the various layers of the OSI model.
(b) Show, by means of a diagram, how the TCP/IP reference model is different from the OSI-7 reference model? Why is the TCP/IP model widely used?
(c) Two popular Mail Access Protocols used nowadays are POP3 and IMAP.
(i) What is the function of a Mail Access Protocol?
(ii) Describe briefly the two download modes of POP3.
(iii) From an ISP's point of view, POP3 and IMAP differ in an important way. Imagine that you were called in to advise an ISP on which protocol it should support. What considerations would you bring up?