Home - CNDS - Joke

1

Estimate, to the nearest millisecond, the time taken for a data packet to travel from the second PC from the back in lab LB43 (Craiglockhart Campus, Napier) to the central square in Milan, Italy. Where are the likely slow points, and where are errors likely to occur?

Note that there is no need to show any working out, or mathematical formulas, as a single number will do. Assume that it is 9:15pm on a rainy Tuesday in April, and that someone has just crashed a computer in a lab adjacent to LB43 (Hint: It is more than 10ms, and less than 10 seconds).   (25)

2

(a)

Show, using illustrations (with good use of colour), how data packet travel from a council estate in Coatbridge to Stonybridge. How does this differ from data packets which originate from Wishaw? From Coatbridge, how might the traffic vary to the Glasgow Celtic WWW and the Glasgow Rangers WWW sites? Which is likely to be greater?   (15)

(b)

Describe, in great detail, how Class X IP addresses are used to access WWW sites which have objectionable content. Give examples of these domains which you have accessed, giving exact times and their content. Where on your computer might these files be stored, and why are the data packets invisible to the Internet? [10]

3

(a)

Explain the technology that allows gigabit per second speeds down a standard piece of door bell cable. How is it possible to transmit data, and also front door bell signals, along the same cable?

Carefully explain how the door bell signals could be decoded by any host on the Internet, and then how these could be used to open the door (Note: do not use the example of a person actually getting up to go to the door). Also, what happens when the user uses the wrong voltage rating for the front door bell battery? [12]

(b)

Show how it is possible to avoid network collision in Ethernet with users waving flags when they are about to send data. How is priority of transmission built into this system, and how is it difficult for a user to predict when they are about to receive data. Also, how might different coloured flags be used? Finally, if different coloured t-shirts are used instead, what effect does this have on the latency of the data packet. that coloured flags would not.   [13]

4

(a)

Estimate the length of the cable, to the nearest inch, that connects Merchiston to Craiglockhart and what colour is the outer coating? [5]

(b)

To the nearest thousand, how many users currently connect to the Internet (1pm, Wednesday, 24 January 2001)? Determine, using complex mathematical formulas, the percentage of people who, at this current hour, connect to the Internet in each of the countries around the world. If you have time illustrate these using coloured pens/pencils (Note: marks will be given for neatness, and also the usage of colours. If possible use light colours for areas where there is a light connectivity to the Internet, and dark colours for the rest. You can ignore Antarctica.) [20]

5

(a)

Explain, in great detail, why it is not possible to get connected to your free unmetered access ISP after 6pm at night. Also describe how they will cut you off, just as your accessing important information. What is the protocol that they use so that you cannot connect back to the Internet for at least eight hours after you have been disconnected.   (12)

(b)

What is the IP address, and MAC address of the www.intel.co.jp server? What protocol is used if you know the MAC address of a host in another continent and you want to determine its processor type (13)

6

(a)

Describe the purpose of each of the following smilies:

(9--+)

(#@-0)   (5) 

(b)

Explain the operation of the protocol that converts the data bits from one language (such as English bits) into the bits for another language (such as Chinese bits). Using this protocol, describe how the English bits of 0 and 1, are converted into NAW and AYE, in Scottish. At what location between Scotland and England does the conversion take place? (20)