UNIVERSITY OF BOLTON CREATIVE TECHNOLOGIES COMPUTER NETWORKS AND SECURITY SEMESTER ONE EXAMINATIONS 2015/2016 WIRELESS NETWORKS AND SECURITY

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1 [CRT02] UNIVERSITY OF BOLTON CREATIVE TECHNOLOGIES COMPUTER NETWORKS AND SECURITY SEMESTER ONE EXAMINATIONS 2015/2016 WIRELESS NETWORKS AND SECURITY MODULE NO: CPU5009 Date: Thursday 14 th January 2016 Time: 10:00 12:00 INSTRUCTIONS TO CANDIDATES: There are SIX questions on this paper. Answer QUESTION 1 and any THREE OTHER questions. All questions carry equal marks. Marks for parts of questions are shown in brackets. Silent electronic calculators may be used provided that data and programme storage memory is cleared prior to the examination

2 Page 2 of 8 1. This is a multiple choice question consisting of seventeen parts. Each part has five possible answers of which ONLY ONE is correct. To indicate your selection write down the question number and indicate which answer you have selected. For example in the Example question below, February has less than thirty days, so write down the question number and answer c). Example Question: which month has less than thirty days? a) January b) March c) February d) October e) May 1) Which of the following would provide the most secure pre-shared key encryption in a wireless LAN? a) WEP b) WPA c) WPS d) 802.1x and EAP e) WPA2 2) When can an access point transmit? a) Whenever it wants to b) PHY=free, NAV=1, Channel=free, Slot=1 c) PHY=free, NAV=0, Channel=free, Slot=0 d) When data is ready to send e) PHY=free, NAV=1, Channel=free, Slot=0 Question 1 continued over

3 Page 3 of 8 Question 1 continued 3) Which of the following received signal levels (RSL) does not provide the required fade margin? a) RSL = -63 db, sensitivity = -80 db, required margin = 16 db b) RSL = -74 db, sensitivity = -90 db, required margin = 15 db c) RSL = -58 db, sensitivity = -80 db, required margin = 20 db d) RSL = -61 db, sensitivity = -85 db, required margin = 15 db e) RSL = -59 db, sensitivity = -75 db, required margin = 17 db 4) Device 1 communicates with Device 2 over a 300 Mbps link. Device 2 communicates with Device 3 over a 54 Mbps link. Device 3 communicates with Device 4 over a 144 Mbps link. What is the effective throughput between Device 1 and Device 4? a) 300 Mbps b) 144 Mbps c) 54 Mbps d) 198 Mbps e) 498 Mbps 5) Which of the following is normally the largest source of attenuation in a correctly functioning wireless link? a) Transmitter output power b) EIRP c) Antenna choice d) FSPL e) Lightning arrestors Question 1 continued over

4 Page 4 of 8 Question 1 continued 6) Which of the following would provide non-overlapping g wireless channels? a) 4, 9 and 13 b) 4 and 10 c) 2 and 6 d) 36, 40 and 44 e) 4 and 8 7) Which of the following is an example of a Man in the Middle (MITM) attack? a) Aircrack-ng b) InSSIDer c) Cain and Abel d) Evil twin e) Reaver 8) What is the approximate wavelength of a 17 GHz signal? a) 18 metres b) 1.8 metres c) 0.18 metres d) metres e) 17 metres 9) Which of the following is not a wireless networking technology or system? a) ZigBee b) WiMAX c) ALOHAnet d) Bluetooth e) LEO Question 1 continued over

5 Page 5 of 8 Question 1 continued 10) Which of the following best describes co-channel interference? a) Impairment to one signal due to the presence of another signal on the same channel b) Impairment of a signal due to the presence of a signal on a nearby frequency c) Impairment of a signal due to the use of the a 5GHz band d) Impairment to WLAN throughput due to the incorrect choice of AP antenna e) Impairment due to the installation of more than one WLAN NIC on the same host 11) Which of the following is not used in radio analysis? a) dbi b) dby c) db d) dbw e) dbm 12) What is a radio power output of 32 milliwatts expressed in dbm? a) dbm b) 32 dbm c) 3.2 dbm d) 320 dbm e) dbm 13) Which of the following mechanisms helps to overcome hidden nodes in wireless networks? a) IEEE b) Hidden Node Algorithm (HNA) c) RTS/CTS d) DSR/DTR e) FHSS Question 1 continued over

6 Page 6 of 8 Question 1 continued 14) What does OFDM stand for? a) Orthogonal frequency-duplex multiplexing b) Optimal frequency-detection mechanism c) Orthogonal frequency-duplex mechanism d) Orthogonal frequency-division multiplexing e) Optimal frequency-duplex mechanism 15) When dealing with radio waves, what is the relationship between wavelength and frequency? a) Frequency = Speed of light in vacuum = Wavelength b) Frequency x Speed of light in vacuum = Wavelength c) Wavelength x Frequency = Speed of light in vacuum d) Wavelength Frequency = Speed of light in vacuum e) Wavelength x Speed of light in vacuum = frequency 16) Which of the following provides the highest throughput? a) g b) a c) b d) n e) ac 17) Which of the following allows access points to be located away from a mains electricity supply? a) MIMO b) PoE c) CDMA d) RTS/CTS e) GSM

7 Page 7 of 8 2. a) A power meter at the output of a wireless amplifier reads 35 dbm. Calculate the output power in watts. Explain what is meant by half power points and what the value is in this example. (6 marks) b) What is the Fresnel Zone in radio systems? Include details of techniques that improve radio link performance if the path is partially obstructed or suffers from reflections. (8 Marks) c) An antenna has a gain of 20 dbi, an access point has an output power of 15 dbm and the cable connecting them has a loss of 3 db. Calculate the EIRP emitted from the antenna. (6 marks) d) Explain what is meant by reflection in the context of radio waves and describe how this affects radio coverage. (5 marks) 3. a) Explain which devices or device configuration will block the operation of Extended Service Set mobility and therefore which network devices should and should not be used in this network scenario. (7 Marks) b) Compare and contrast a 5GHz wireless to 2.4 GHz wireless specifications such as g and suggest a situation where a might be beneficial. (9 Marks) c) Describe the operation of an access point in root mode, bridge mode and repeater mode. (9 Marks).

8 Page 8 of 8 4. a) Describe the mechanism which enables hidden nodes in a WLAN network to communicate effectively. (9 Marks) b) Describe FDMA and TDMA and use diagrams to illustrate the relationship between frequency and time for both protocols. (8 Marks) c) Draw a typical azimuth pattern for a Yagi antenna having a beam width of 15 degrees. Explain how antenna can be misaligned on side lobes. (8 marks) 5. a) With the aid of a diagram, describe the operation of Typhoid Adware and why it is relatively difficult to prevent. (16 Marks) b) Describe how MAC address filtering works and explain why this should not be relied upon to secure a WLAN. (9 marks) 6. a) Discuss, in detail, the vulnerability in WPS which allows a side channel attack against WPA2 encryption and suggest the best response to this exploit. (15 Marks) b) Outline the concept of a rogue access point, discuss why they are a potential business risk and suggest how an organisation might respond to the threat. (10 marks) END OF QUESTIONS