2 Julia inputs personal data into her computer. She stores three copies of the data using a hard disk drive (HDD), a solid state drive (SSD) and a USB flash memory drive. (a) Identify three devices Julia can use to input personal data into her computer. Device 1 … Device 2 … Device 3 … [3] (b) Six statements are shown about HDDs, SSDs and USB flash memory drives. Tick (✓) to show which statements apply to each type of storage. Some statements can apply to more than one type of storage. Statement HDD (✓) SSD (✓) USB flash memory drive (✓) it has no moving parts it is non-volatile it can use NAND gates to store data it uses magnetic properties to store data it has the smallest physical size it has the slowest read/write speeds [6] (c) Julia uses a USB connection to transfer data onto her USB flash memory drive. (i) One benefit of using a USB connection is that it is a universal connection. State two other benefits of using a USB connection. Benefit 1 … … Benefit 2 … … [2] (ii) Identify the type of data transmission used in a USB connection. … [1]

2(a) Any three from: − Keyboard − Mouse − Microphone − Keypad − Touchscreen − Touchpad 3 2(b) One mark for each correct row. Statement HDD () SSD () USB flash memory drive () it has no moving parts   it is non-volatile    it can use NAND gates to store data   it uses magnetic properties to store data  it has the smallest physical size  it has the slowest read/write speeds  6 2(c)(i) Any two from: − It cannot be inserted incorrectly − Supports different transmission speeds − High speed transmission − Automatically detected (not connected) // automatically downloads drivers − Powers the device (for data transfer) − Backward compatible 2 2(c)(ii) − Serial 1

3 (a) Six statements are given about methods of data transmission. Tick (✓) to show if each statement applies to serial simplex, parallel simplex, parallel half-duplex or serial duplex data transmission. Some statements may apply to more than one data transmission method. Statement Serial simplex (✓) Parallel simplex (✓) Parallel half-duplex (✓) Serial duplex (✓) bits are transmitted along a single wire data is transmitted in both directions it is only suitable for distances less than 5 metres bits from the same byte are transmitted one after the other data may not arrive in the correct sequence data is transmitted in both directions, but only one direction at a time [6] (b) A Universal Serial Bus (USB) connection can be used to transmit data from a mobile device to a computer. Give three benefits of using a USB connection for this purpose. Benefit 1 … … Benefit 2 … … Benefit 3 … … [3]

3(a) One mark per each correct row. Statement Serial simplex () Parallel simplex () Parallel half-duplex () Serial duplex () bits are transmitted along a single wire   data is transmitted in both directions   it is only suitable for distances less than 5 metres   Bits from the same byte are transmitted one after the other   data may not arrive in the correct sequence   data is transmitted in both directions, but only one direction at a time  6 3(b) Any three from: − Can charge/power the mobile device (at the same time) − (Uses serial transmission so) data less likely to be skewed / corrupted − Universal / industry standard / connection − Cable can only be plugged in one way // Cannot be inserted incorrectly − Fast transmission speed − Backward compatible − Supports different transmission speeds − Automatically detects device // Automatically downloads drivers 3

8 Four 7-bit binary values are transmitted from one computer to another. A parity bit is added to each binary value creating 8-bit binary values. All the binary values are transmitted and received correctly. (a) Identify whether each 8-bit binary value has been sent using odd or even parity by writing odd or even in the type of parity column. 8-bit binary value Type of parity 01100100 10010001 00000011 10110010 [4] (b) An error may not be detected when using a parity check. Identify why an error may not be detected. … … [1] (c) The data is sent using parallel half-duplex data transmission. (i) Describe how data is sent using parallel half-duplex data transmission. … … … … … … … … [4] (ii) State two drawbacks of using parallel data transmission. Drawback 1 … … Drawback 2 … … [2]

8(a) − Odd − Odd − Even − Even 4 8(b) Any one from: − there is a transposition of bits − it does not check the order of the bits (just the sum of 1s/0s) − even number of bits change − incorrect bits still add up to correct parity 1 8(c)(i) Four from: − Multiple bits are sent at the same time − Uses multiple wires − Data is sent in both directions … − … but only one direction at a time 4 8(c)(ii) Any two from: − Bits may arrive skewed − More expensive to setup/manufacture/purchase cable − Limited distance − More prone to interference/error 2

10 Jermain uses the Secure Socket Layer (SSL) protocol for secure transmission when sending data using the internet. (a) Explain how the SSL protocol secures the data for transmission. … … … … [2] (b) Identify an alternative protocol that could be used for secure transmission of data using the internet. … [1] (c) Give two ways that a user can identify if a website uses secure data transmission. 1 … … 2 … … [2]

10(a) − Enables an encrypted link (between the browser and the web server) // It encrypts the data − … based on the authentication of an (SSL) certificate // and will only send it if the certificate is authentic 2 10(b) − Transport Layer Security // TLS 1 10(c) Any two from: − URL begins with HTTPS − Padlock symbol is locked − Check the certificate is valid 2

1 Tina is creating a website for charity events. She uses HTML to create the website. (a) State what is meant by HTML. … … [1] (b) She uses the hexadecimal colour code #43B7F0 as the background colour for her website. (i) State whether background colour is an example of structure or presentation, in the website. … [1] (ii) The hexadecimal colour code #43B7F0 is stored in three 8-bit registers. Give the 8-bit binary values for each part of the hexadecimal code. 43 B7 F0 [6] (c) Tina uses a microphone to record a welcome message for her website. (i) State whether the microphone is an input or output device. … [1] (ii) She wants to compress the recording to make sure that the file is as small as possible for the website. Identify which type of compression she should use and describe how this would compress the file for the website. Type of compression … Description … … … … … … … … [4] (iii) Give two benefits of compressing the file for the website. Benefit 1 … … Benefit 2 … … [2] (d) Tina will use the TLS protocol in her website when selling tickets to people for different charity events. This makes sure that their personal data is transmitted securely. (i) Identify the two layers that are present in the TLS protocol. Layer 1 … Layer 2 … [2] (ii) Explain how data is sent securely using the TLS protocol. … … … … … … … … … … … … [6] (e) Tina is concerned about security threats to her web server. (i) Identify three security threats to her web server that Tina might be concerned about. 1 … 2 … 3 … [3] (ii) Tina installs a proxy server to help protect her website from security threats. Describe how the proxy server will help protect the website. … … … … … … … … [4]

1(a) Any one from: − Hypertext Mark-up Language − Web authoring language // language used to write/create websites/web pages 1 1(b)(i) − Presentation 1 1(b)(ii) One mark per each nibble: 43 0 1 0 0 0 0 1 1 B7 1 0 1 1 0 1 1 1 F0 1 1 1 1 0 0 0 0 6 1(c)(i) − Input 1 1(c)(ii) One from: − Lossy (compression) Any three from: − A (compression) algorithm is used − Removes redundant/unnecessary data from the file − Removes sounds that cannot be heard by the human ear/background noise − Reduces sample rate − Reduces sample resolution − Data is permanently removed // original file cannot be re-instated − Perceptual music shaping is used NOTE: If lossless given, marks can be awarded for a correct description of lossless as follow through. Any three from (lossless): − A (compression) algorithm is used − Repeating patterns are identified − … are replaced with a value − … and indexed − No data is permanently removed // original file can be re-instated − Suitable example of a lossless algorithm 4 1(c)(iii) Any two from: − Quicker for her to upload − Quicker for users to download − Won’t slow website down as much when loading − Takes up less storage space 2 1(d)(i) − Handshake (layer) − Record (layer) 2 1(d)(ii) Any six from: − Client/browser requests secure connection to server − Client/browser requests the server to identify itself − Server provides a digital certificate − Client/browser validates the certificate − Client/browser send signal back to server (to begin transmission) − Session caching can be used − A session key is generated − Encryption method is agreed // data is encrypted 6 1(e)(i) Any three from: − Hacking − Denial of service (DoS) attack − Virus − Malware NOTE: Three different type of malware can be awarded 3 1(e)(ii) Any four from: − Acts as a firewall − Monitor/filters/examines incoming and outgoing traffic − Rules/criteria for traffic can be set // blacklist/whitelist set − Blocks any traffic that does not meet criteria … − … and can send a warning message to the user − Stop the website failing in a DoS attack // DoS attack hits the proxy server and not the webserver 4

Cambridge O Level Computer Science · 2210

O-Level Computer Science (2210) Data transmission past paper questions

Revise O-Level Computer Science (2210) — Data transmission with real Cambridge past-paper questions grouped by topic, each shown with its marking scheme. Working one topic at a time targets exactly the skill each question tests.

50 free questions from 2016–2021, each with its marking scheme. Open the full topical bank to filter by subtopic, paper, and year.