Suppose Alice, with a Web$-$based e$-$mail account $($such as Hotmail or Gmail$),$ sends a

message to Bob, who accesses his mail from his mail server using IMAP. Discuss how

the message gets from Alice$$s host to Bob$$s host. Be sure to list the series of application$-$

layer protocols that are used to move the message between the two hosts.

B$.$ In BitTorrent, suppose Alice provides chunks to Bob throughout a $30-$second interval.

Will Bob necessarily return the favor and provide chunks to Alice in this same interval?

Why or why not?

C$.$ Consider that you are sending an email with a message body size of $50$ KB using SMTP

over a TCP connection. The following details are given:

The round$-$trip time $($RTT$)$ between the client and the mail server is $100$ milliseconds.

The email is transmitted over a link with a transmission speed of $1$ Mbps$.$

It takes one RTT to establish the TCP connection.

Assume that it takes one RTT to initiate the message transfer after the TCP connection is

established and that the transmission time for the message body is based on the link

speed.

a$)$ How long does it take to send the email from the client to the server using SMTP$?$

b$)$ If you were to send an email with a $100$ KB attachment, how much time would it take

using SMTP$?$