COMP361 Lab -  Week 05 - Review Questions on Chapter 2

Note:  the review questions below were chosen from the back of Chapter 2 of K&R

Problem 1:  List four nonproprietary  Internet applications and the application-level protocols that they use.

 

Problem 2:  What information is used by a process running on one host to identify a process running on another host?

 

Problem 3:  What is meant by a "handshaking protocol"?

 

Problem 4:  What is the difference between persistent http with pipelining and persistent http without pipelining?

 

Problem 5:  Suppose Alice uses a Web-based email account (such as Hotmail) to send a message to Bob, who accesses his mail from his mailserver using POP3. Discuss how the message gets from Alice's host to Bob's server. Be sure to list the series of application layer protocols that are used to move the message between the two hosts.

 

Problem 6:  Each internet host has at least one local name server and one authoritative name server. What role does each of these services have in DNS?

 

Problem 7:  Is it possible that an organization's Web server and mail server have exactly the same name, e.g., foo.com?

 

Problem 8:  The UDP server described in Section 2.8 of the book only needed one socket whereas the TCP server described in 2.7  needed  2 sockets.  Why?  If the TCP server were to support n simultaneous connections, each from a different client host,  how many sockets would the TCP server need?

 

Problem 9:    For each of the below, write True or False.

  1. Suppose a user requests a web page consisting of some text and two images.  For this page the client will send one request message and receive three response messages.
  2. Two distinct web pages, e.g.,  www.mit.edu/research.html and www.mit.edu/students.html, can be sent over the same persistent connection.
  3. With nonpersistent connections between browser and origin server it is possible for  a single TCP segment to carry two distinct HTTP request messages..
  4. The Date:  header in the HTTP response message indicates when the object in the response was last modified.

 

Problem 10:    Consider an HTTP client that wants to retrieve a web document at a given URL.  The IP address of the HTTP server is initially unknown.  The Web document at the URL has one embedded GIF image that resides as the same server as the original document.  What transport and application layer protocols are needed in this scenario?

 

Problem 11:    Suppose within your web browser you click on a link to obtain a web page. Suppose that the IP address for the associated URL is not cached in your local host so that a DNS lookup is necessary to obtain the IP address. Suppose that n DNS servers are visited before your host receives the IP address from DNS and that then successive visits incur an RTT of RTT1, RTT2, ..., RTTn. Further suppose that the web page associated with the link contains exactly one object,  a small amount of html text.  Let RTT0 denote the RTT between the local host and the server containing the object.  Assuming zero transmission time of the object, how much time elapses from when the client clicks on the link until the client receives the object?

 

Problem 12:    Assume the same setup as Problem 10 but now add the fact that the html file will indexes three very small objects on the same server. Neglecting transmission times how much time elapses with (1) non-persistent HTTP with no parallel TCP connections, (2) non-persistent HTTP with parallel connections and (3) persistent HTTP with pipelining? Explain your answers.