The Software Process - Courseweb - Xavier University

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					                            Xavier University – Ateneo de Cagayan
                              Department of Computer Science
                                FINAL EXAMINATION
                              CS 55 Computer Networks

Essay/Short Answer Question/Problem Solving. In your own words, answer the following

questions as briefly and concisely as possible – 8 items (10 points each for a total of 80 points).

1. Using a block diagram, describe the major components of a communication system. Show an

   example using a specific data communication scenario (e.g. dial-up Internet access via a local

   Internet Service Provider or accessing remote computers over the telephone network). What

   are the things that you need in terms of hard ware and software?

2. Enumerate and describe the seven layers of the Open Systems Interconnect (OSI) Reference

   Model then describe the main layers of the Transmission Control Protocol/Internet Protocol

   (TCP/IP) and how it relates to the OSI reference model. Is there a one-to-one mapping

   between the TCP/IP and OSI layers? Show an example of layering by mapping the

   components of a network you are familiar with to the OSI RM or TCP/IP layers.

3. Rank twisted pair, coaxial cable and fiber optics with respect to speed, cost and resistance to

   “noise”. Which is fastest? Which is least expensive? Which is less error prone? Use a table to

   describe your answers. What is the ideal medium to cable a room, link building floors or

   connect buildings on a local area or campus network?

4. Describe how parity checking (PC) works? Cyclic redundancy check (CRC)? Longitudinal

   redundancy check (LRC)? Which is better at detecting errors, PC or CRC? What is the

   difference between CRC and LRC?
5. Describe the three basic local area network (LAN) topologies? What LAN transmission

   media is suitable for each of the topologies? How does topology affect the media access

   control (MAC) protocol used in a LAN?

6. Using the OSI Reference Model as a guide, describe the functions of networking devices

   such as repeaters, bridges, routers and gateways. What are the similarities and differences

   between an Ethernet hub and switch?

7. What is an IP address? A network mask? How do IP addresses relate to Fully Qualified

   Domain Names (FQDNs) and the Domain Name Service (DNS). Describe how data packets

   are routed or transmitted over the Internet (i.e., IP routing).

8. Given the different types of data transmission media/channels - private lines, switched lines,

   leased lines, coaxial cable, fiber optics, microwave, satellite, etc - which would be the most

   suitable for the following applications and why? (a) A research corporation is evaluating

   solar energy systems. It has data collection devices attached to several experimental wind and

   solar collectors. A large, continuous volume of data is transmitted to the computer center,

   which is 10 miles from the test grounds. The computer center can be seen from the test

   grounds. (b) A major car rental agency has decide to rationalize its inventory and reservation

   system. Approximately 75% of the reservation requests are resolved by the regional center

   and the remaining 25% must be forwarded to another regional processing center. The peak

   amount of data to be transmitted to another center is approximately 10,000 characters per

   minute. This also means that each regional center will receive approximately 10,000

   characters per minute.

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