NASS 2019 P1 Solution

Sec 4 O Level Prelim 2019 Computing Paper 1 Marking Scheme 1 (a) 203 (with working) (b) AD (with working) (c) Manufacturer identification number Device serial number (d) 27 and not 31. Not the one. 2 (a) A bit is a binary digit which can take on the value of either 0 or 1. A byte is a binary number made up of eight bits. (b) 2.45 GB 2048 B (c) Devices with label Correct connecting lines (d) Internet Modem Router Laptop Printer Smartphone 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 (a) Advantage: A magnetic hard disk is relatively cheaper than solid-state memory card. [reject: storage capacity (a solid-state memory card can also provide large storage capacity)] Disadvantage: A magnetic hard disk is culnerable to drops and mechanical shocks while a solid-state memory card is not as vulnerable to drops and mechanical shocks. (b) Optical external storage / DVD / solid state external hard disk (c) Data is entered using an input device and converted into a form that the computer can understand. This data may be temporarily stored in a processor register. Instructions from the running application are interpreted by the processor’s control unit. These instructions may request the data to be processed by the processor’s ALU. The control unit may then redirect the processed data to an output device for display in a form that users can understand. 4 (a) (i) Surnames as password can be easily guessed by intruder. (ii) Hard-to-guess passwords consist of a mixture of lower-case letters, upper-case letters, numbers and symbols. (b) (i) Phishing is the use of emails and fake wbesites that appear to be from reputable companies in order to steal personal information such as passwords from users. (ii) Any ONE sign: - email asks for persona data or confidential information. - email uses generic greeting. - email has inaccurate logos OR grammatical and spelling errors. - email seems to come from an address or contact that does not match the supposed source of email. - email contains hyperlinks with destinations that do not match what the hyperlink text says or are otherwise unexpected. - tone of email is excessively urgent or threatening. (c) Two-factor authenticatio