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BSc (Hons) Business Information Systems BSc (Hons) Web Technologies BIS/08/PT - BWT/09/FT Examinations for 2009 - 2010 / Semester 1 MODULE: NETWORKS/NETWORKING ESSENTIALS MODULE CODE: CAN1102/CAN1103 DURATION: 2 HOURS READING TIME: None Instructions to Candidates 1. Answer both Section A and any 2 questions from Section B 2. Always start a new question on a fresh page for Section B. 3. Total marks: 100 4. Use of silent calculators is allowed in the Examination Room. This questionnaire contains 29 Questions and consists of 9 pages. Page 1 of 9 SECTION A The following 25 multiple-choice questions contain only one correct answer. You do not need to copy the questions, write your response legibly i.e. (a), (b), (c) or (d) on your script in five columns with the respective question number. 1. (a) (b) (c) (d) How many layers does the TCP/IP model have? 7 4 or 5 3 Variable 2. (a) (b) (c) (d) Which topology requires a multipoint connection? Mesh Star Bus Ring 3. (a) (b) (c) (d) Which of the following usually operate on a Local Area Network (LAN)? Ethernet Internet Arpanet None of the above 4. (a) (b) (c) (d) Which layer in the ISO:OSI model is concerned with logic transmission only? Physical layer Network Layer Data Link Layer Transport Layer 5. (a) (b) (c) (d) What is the direct purpose of layered communication models? Reduce complexity Increase transmission rate Improve reliability Enhance security Page 2 of 9 6. (a) (b) (c) (d) What does FEC stands for? Forward Error Correction Forward Error Connection Full Event Correction Full Error Correction 7. (a) (b) (c) (d) What does a CSMA transmitter do when it has data to transmit? Send out an RTS to all other transmitters Transmit the data immediately Sense the channel to see if idle Broadcast “jamming” signal to all other nodes 8. (a) (b) (c) (d) Which of the following device does not provide traffic isolation? Router Hub Bridge Switch 9. (a) (b) (c) (d) How many bits are there in an IPv4 address? 16 32 64 4 10. (a) (b) (c) (d) Which one is a feature of IPv6, different from IPv4? Fragmentation 128-bit address Variable length header A field of “more fragments” (MF) 11. In ARP, what does node A do first if it wants to get the physical address of node B if node B's IP address is known? (a) Check nearest router's routing table (b) Send a unicast packet to node B to ask for the physical address (c) Check its ARP table (d) Broadcast an ARP request over the network 12. (a) (b) (c) (d) Which of the following is NOT a characteristic of a Token Ring network? Token flows either clockwise or anticlockwise but not in both direction A node must capture the token before data can be transmitted Token must be released by the node after data transmission Token ring networks are robust and if one node fails it does not affect the other nodes Page 3 of 9 13. (a) (b) (c) (d) Which of the following is NOT true about the MAC address? It uniquely identifies a network adapter It can be changed when a host is moved to another network. It is 48-bits in size It is usually stored in a ROM chip on the network adapter. 14. Which of the following device would you use to interconnect two LANs which are using two different LAN technologies i.e. one LAN using Ethernet and the other LAN using Token Ring? (a) Hub (b) Bridge (c) Router (d) Switch 15. (a) (b) (c) (d) Which of the following is NOT true about a 10Base-T standard? The transmission speed is 10 Mbps It uses Twisted pair cables. It uses a baseband signal It is easy to detect cable breaks and to add or remove nodes. 16. (a) (b) (c) (d) What does CDMA stands for? Code Diversion Model Access Coding Discrete Model Access Code Division Model Access Code Division Multiple Access 17. (a) (b) (c) (d) Which of the following does NOT apply to Bluetooth Technology? Small range of wireless connection It uses frequency of 5 – 6 GHz and is uni-directional. It uses a frequency of 2.4 – 2.5 GHz and is omni-directional. It allows devices such as phone, camera, printers, notebooks to connect. 18. (a) (b) (c) (d) Which of the following is not an application layer protocol? SMTP SSL HTTP FTP 19. (a) (b) (c) (d) What is the port number associated with HTTP? 25 21 23 None of the above Page 4 of 9 20. (a) (b) (c) (d) What is the default subnet mask for a Class A network? 255.255.255.0 255.255.255.255 255.255.0.0 None of the above 21. You are asked to create 10 Class C subnets with at least 10 hosts per subnet. Which subnet mask must you use? (a) 255.255.255.192 (b) 255.255.255.224 (c) 255.255.255.240 (d) 255.255.255.248 22. (a) (b) (c) (d) HDLC is an acronym for ____. high-duplex line communication high-level data link control half-duplex digital link combination host double-level circuit 23. In IEEE 802.11, a ____ is made of stationary or mobile wireless clients and an optional central base station, known as the access point (AP). (a) ESS (b) BSS (c) CSS (d) None of the above 24. (a) (b) (c) (d) The ____ layer of Ethernet consists of the LLC sublayer and the MAC sublayer. data link physical network none of the above 25. (a) (b) (c) (d) Fast Ethernet has a data rate of ____ Mbps, 10 100 1000 10,000 [25 x 2 marks] Page 5 of 9 SECTION B ATTEMPT ANY TWO QUESTIONS Question 26 (25 marks) (a) Name 3 popular electronic mail access protocols? [3 marks] (b) i. What is DNS? ii. Briefly, describe what it does and how it works? iii. Why does DNS use a distributed approach as opposed to a single server? [2+3+2 marks] (c) HTTP supports both non-persistent and persistent connections. i. Describe each type of connection and state which HTTP protocol version supports each type? ii. How and where is the type of connection specified in the HTTP protocol? [6+2 marks] (d) Assume that a new application layer protocol is developed for video conferencing application. Which transport layer protocol do you think will be used and why? [3 marks] (e) FTP is said to have an “out-of-band” connection. Explain what it means? [4 marks] Page 6 of 9 Question 27 (25 marks) (a) Describe briefly the difference between flow control and congestion control in relation to a connection-oriented protocol such as TCP. [6 marks] (b) What is the initial rate of data transfer in the slow start phase of TCP congestion control, if the MSS is 1060 bytes and an average RTT of 200 milliseconds? [2 marks] (c) Each host on the Internet is currently assigned an IP address 32 bits long (IPv4). IPv4 addresses are usually written as a series of four decimal numbers. IPv4 addresses traditionally belong to one of five classes of address, depending on the type of network. i. Describe the structure of Class C address and a type of network it is suited for. ii. Give two advantages of creating subnets within a larger network. iii. On an isolated network two hosts have been configured to work on the same subnet with IP addresses 10.10.201.254 and 10.15.201.254. Can this configuration work? What would the subnet mask need to be? iv. Give five differences between IPv6 and IPv4? [3+2+4+5 marks] (d) Describe very briefly the purpose of the following protocols: i. DHCP ii. ICMP iii. RARP [3 marks] Page 7 of 9 Question 28 (25 marks) (a) The IEEE 802 series of standards describe both the Physical and Data Link layers of their respective technologies. Two important standards are 802.3 and 802.5, respectively known as CSMA/CD (Ethernet) and Token Ring. i. Explain how CSMA/CD operates and describe how Ethernet deals with collisions. ii. Give the structure of a typical Token Ring frame and explain how communication is effected in a Token Ring Network. [4+4 marks] (b) A datagram of 3000 bytes has to travel over a network with a MTU size of 1000 bytes. Explain how fragmentation can be used to solve this problem. You should give the value of the 3 key fields used in fragmentation for each fragment created. [8 marks] (c) Nowadays many companies are shifting towards the IEEE 802.11x standard for extending their network. i. Outline two popular flavours of this wireless standard. Elaborate on the operating frequency, range and speed of each flavour. ii. What are the two modes of operation of this standard and explain the difference between the two. iii. Mention one security issue with this wireless technology and explain how this issue can be addressed. [3+4+2 marks] Page 8 of 9 Question 29 (25 marks) (a) Mention the five main security services. [5 marks] (b) What is a passive attack? Give an example of passive attack? [4 marks] (c) What four types of active attacks and mention their respective attacks to which security services? [4 marks] (d) Distinguish between authentication and non-repudiation. [4 marks] (e) Which type of algorithms can be used to provide the following security services: i. Message integrity ii. Message integrity and authentication [4 marks] (f) Describe how public key cryptography can be used to provide message confidentiality when Alice wants to communicate with Bob. [4 marks] ***END OF PAPER*** Page 9 of 9