a$)$ Ahmad is buying a mobile Internet data subscription from an Internet Service Provider $($ISP$)$ called JACOM while visiting Japan for one week. In the contract he has noticed that JACOM only provide best$-$effort service. Imagine you are Ahmad$$s knowledgeable tour guide, please explain to Ahmad why the ISP can only provide best$-$effort services but not a guaranteed service. $(6$ marks$)$

b$)$ As both Transmission Control Protocol $($TCP$)$ and User Datagram Protocol $($UDP$)$ use port numbers, what are these port number used for? What is meant by the term well$-$known port numbers and give an example of a well$-$known port numbers with its corresponding application.

$(6$ marks$)$

c$)$ What is the difference in the quality of service $($QoS$)$ offered to applications by the TCP and UDP protocols. $(6$ marks$)$

d$)$ Explain clearly how a network connection is established between a user and server through the internet using the TCP protocol with the help of a diagram. $(6$ marks$)$

e$)$ Explain clearly how a network connection is terminated between a user and server through

the internet using the TCP protocol with the help of a diagram.

marks$)$