NASS 2019 P1

Name: .............................................................................. Register no: ............. Class: ...... NGEE ANN SECONDARY SCHOOL O PRELIMINARY EXAMINATION COMPUTING 7155/01 Paper 1 Written 23 August 2019 2 hours Candidates answer on the Question Paper. No Additional Materials are required. Instructions to Candidates Write your name, register number and class at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. Approved calculators are allowed. Answer all questions. The number of marks is given in brackets [ ] at the end of each question or part question. You should show all your working. The total number of marks for this paper is 80. Checked by student: _____________________ Date: _________ This document consists of 16 printed pages and 0 blank pages. For Examiner’s Use Marks /80

2 NAS/2019/Prelim/4E/7155/01 1 (a) Convert the binary number 11001011 into a denary number. Show your working. …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… [2] (b) Convert the denary number 173 into a hexadecimal number. Show your working. …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… [2] (c) The MAC address of a device is shown below. Fill in the blanks below to indicate what the two groups of numbers represent. 00:B3:A9:12:C9:31 [2] (d) An IT manager is trying to trace if the device in (c) had gained unauthorized access to the company’s network. Based on the log files of the network, the last 4 bits of the unauthorized device’s MAC address in binary form were identified to be 0111. Check and state if the above device was the unauthorized device. …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… [2]

3 NAS/2019/Prelim/4E/7155/01 2 (a) Information is stored in a computer in units known as bits and bytes. Describe what is meant by a bit and a byte. …………………………………………………………………………………………… …………………………………………………………………………………………… …………………………………………………………………………………………… [1] (b) Convert the following amounts of data in the stated units. (i) 2 450 000 000 B = ______________________ GB (ii) 2 KiB = ______________________ B [2] (c) Jason wants to set up a simple network at home to connect his laptop and smartphone to his wireless printer. He has a wireless router and a modem to provide Internet connectivity to all the devices. In the space below, draw a simple diagram, with labels and connecting lines, to show how all the above-mentioned devices can be connected in his home network. [2]

4 NAS/2019/Prelim/4E/7155/01 (d) A topology describes the physical layout of a network. Draw a line between the description and the correct topology. Topology Description Ring topology A formation in which a common cable or backbone connects all devices, allowing the transmission of data to all the devices connected. A formation in which each computer is paired with a network device such as a hub or switch and connected to one another, allowing data transmission between the network devices. Bus topology A formation in which a network device such as a hub or switch is at the centre of the network with connections to all the other computers. A formation in which each computer is connected to two other computers and data is passed around in the same direction. Star topology A formation in which every computer is connected to one another and data can be transmitted from different computers simultaneously. [3]

5 NAS/2019/Prelim/4E/7155/01 3 Kamil is setting up a new computer system to record television programmes. He wants to be able to record, view and then erase programmes that he does not want to keep. (a) He has chosen to use a magnetic hard disk as an optical storage medium. Explain to Kamil an advantage and a disadvantage of using a magnetic hard disk compared to a solid-state memory card. Advantage: …..………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... Disadvantage: …….…………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... [2] (b) State another type of external storage. …………………………………………………………………………………………... [1] (c) The different parts of the computer system work together so that data can travel via different paths through the computer, which is known as data flow. In the text below, insert five of the following words in the correct place about the following data flow when using input and output devices. Data is entered using the ................................... and converted into a form that the computer can understand. This data may be temporarily stored in a ................................... . Instructions from the running application are interpreted by the processor’s ................................... . These instructions may request the data to be processed by the processor’s ................................... . The control unit may then redirect the processed data to the ................................... for display in a form that users can understand. [5] memory input device processor register device output device data bus ALU control unit address bus

6 NAS/2019/Prelim/4E/7155/01 4 Benjamin logged into his game and discovered his account has been hacked and all the items on his character had gone missing. He went to search for help online. (source: https://us.battle.net/support/en/article/9852) (a) Benjamin uses the password for his game account: benjamintay. (i) Explain to Benjamin why this is a poor password for securing his account. ………………………………………………………………….………………... ………………………………………………………………….………………... [1] (ii) Describe how to create hard-to-guess passwords. ……………………………………………………………….…………………... ……………………………………………………………….…………………... [1]

7 NAS/2019/Prelim/4E/7155/01 (b) Benjamin has successfully regained control of his account. The intruder tries another method to gain access to Benjamin’s account again by using a phishing email. (i) State what is meant by phishing. ………………………………………………………………….………………... ………………………………………………………………….………………... [1] (ii) Describe a tell-tale sign to identify phishing emails. ……………………………………………………………….…………………... ……………………………………………………………….…………………... [1] (c) The gaming website recently adopted a two-factor authentication for users to access their online accounts more securely. Explain what two-factor authentication is, and how it allows secure access to online accounts. …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... [2] (d) Describe the social issues arising from the use of technology in the area of entertainment. …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... …………………………………………………………………………………………... [2]

8 NAS/2019/Prelim/4E/7155/01 5 (a) Identify the logic gate represented by the following truth table. A B X 0 0 1 0 1 0 1 0 0 1 1 0 …………………………………………………………………………………………… [1] (b) Complete the truth table for the Boolean statement: X = ((A NOR B) OR (A