Question

P4. 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). Tips the following questions, indicating where in the HTTP GET message below you find the Tips. GET /cs453/index.html HTTP/1.1Host: gai a.cs.umass.eduUser-Agent: Mozilla/5.0 ( Windows;U; Windows NT 5.1; en-US; rv:1.7.2) Gec ko/20040804 Netscape/7.2 (ax) Accept:ex t/xml, application/xml, application/xhtml+xml, text /html;q=0.9, text/plain;q=0.8,image/png,*/*;q=0.5 Accept-Language: en-us,en;q=0.5Accept- Encoding: zip,deflateAccept-Charset: ISO -8859-1,utf-8;q=0.7,*;q=0.7Keep-Alive: 300Connection:keep-alive a. What is the URL of the document requested by the browser? b. What version of HTTP is the browser running? c. Does the browser request a non-persistent or a persistent connection? d. What is the IP address of the host on which the browser is running? e. What type of browser initiates this message? Why is the browser type needed in an HTTP request message?

Answer 1

a. What is the URL of the document requested by the browser?
The document request was http://gai a.cs.umass.edu/cs453/index.html.
Here the Host field (gai a.cs.umass.edu) indicates the server's name and /cs453/index.html indicates the file name.

b. What version of HTTP is the browser running?
The browser is running HTTP version 1.1. This can be indicated just before Host field.

c.Does the browser request a non-persistent or a persistent connection?
The browser is requesting a persistent connection, as indicated by the Connection: keep alive at last line (Keep-Alive: 300Connection:keep-alive).

d. What is the IP address of the host on which the browser is running?
IP address is not mentioned in HTTP request or message. So it is not possible to tell the IP address by just looking at the HTTP message. You will need the information from the IP datagram(which carries the TCP segments which also carries the HTTP GET request).

e. What type of browser initiates this message? Why is the browser type needed in an HTTP request message?
This message is initiated by Mozilla 5.0 which can be identified by User-Agent: Mozilla/5.0.
This browser type neede in an HTTP request message to send diffrent version of same object to diffrent types of browsers.