Question $6$

$($a$)$ The figure below shows a simplified diagram of how emails are sent by Alice to Bob:

$($i$)$ Briefly describe TWO functions of the UA $($User Agent$).$

$($ii$)$ MTA is the Message Transfer Agent. Briefly describe the functions of the MTA client

at the sender side and MTA server at the receiver side.

$($b$)$ A client needs to access an html file that contains a link to an image on the same server. Are

there any differences between using HTTP $1\mathrm{.}0$ and HTTP $1\mathrm{.}1$ for the connection? Explain

your answer.

$($c$)$ A $1300-$bytes IP datagram is being sent into a link with MTU of $550$ bytes. Suppose the

original datagram has identification number $5678$ and there is no option in the header.

$($i$)$ What is the size of data in the original datagram?

$($ii$)$ What is the MAXIMUM data size in each fragment?

$($iii$)$ How many fragments are generated?

$($iv$)$ For EACH fragment in $($iii$),$ determine their respective sizes in bytes.

$($v$)$ For EACH fragment in $($iii$),$ determine the values of the ID$,$ fragment flag and offset.