Problem $2.$ Consider the following string of ASCII characters that were captured by Wireshark when the browser sent an HTTP GET message $($i$.$e$.,$ this is the actual content of an HTTP GET message$).$ The characters are carriage return and line$-$feed characters $($that is$,$ the italized character string in the text below represents the single carriage$-$return character that was contained at that point in the HTTP header$).$ Answer the following questions, indicating where in the HTTP GET message below you find the answer.

GET $/$cs$453/$index$.$html HTTP$/1\mathrm{.}1$Host: gai

a$.$cs$.$umass.eduUser$-$Agent: Mozilla$/5\mathrm{.}0($

Windows;U; Windows NT $5\mathrm{.}1$; en$-$US; rv:$1\mathrm{.}7\mathrm{.}2)$ Gec

ko$/20040804$ Netscape$/7\mathrm{.}2($ax$)$ Accept:ex

t$/$xml$,$ application$/$xml$,$ application$/$xhtml$+$xml$,$ text

$/$html;q$=0\mathrm{.}9,$ text$/$plain;q$=0\mathrm{.}8,$image$/$png$,*/*$;q$=0\mathrm{.}5$

Accept$-$Language: en$-$us$,$en;q$=0\mathrm{.}5$Accept$-$

Encoding: zip,deflateAccept$-$Charset: ISO

$-8859-1,$utf$-8$;q$=0\mathrm{.}7,*$;q$=0\mathrm{.}7$Keep$-$Alive: $300$

Connection:keep$-$alive

What is the URL of the document requested by the browser?

What version of HTTP is the browser running?

Does the browser request a non$-$persistent or a persistent connection?

What is the IP address of the host on which the browser is running?

What type of browser initiates this message? Why is the browser type needed in an HTTP request message?

Problem $3.($Option$1)$ What is the difference between MAIL FROM: in SMTP and From: in the mail message itself?

$($Option$2)$ Send an email to acsc$415$@gmail.com with fake usca.edu email address. Please remember to put real name inside of the email body. The mail server that you can relay your email is on campus with ip address $129\mathrm{.}252\mathrm{.}199\mathrm{.}171.$ You may access it through school VPN if you are off campus. The ip address may update daily, please do not share it with students outside of the class.

Problem $4.$ How does SMTP mark the end of a message body? How about HTTP$?$ Can HTTP use the same method as SMTP to mark the end of a message body? Explain.