Cambridge A Level Information Technology (from 2017) 9626 — 2022 Oct/Nov Paper 3 · Variant 3

1 Explain how each of the following is used in a network. (a) web server ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (b) mail server ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (c) print server ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2]

Mark scheme: Question Answer Marks 1(a) Two from: 2 Store html documents (on secondary storage devices) Store text/images/style sheets/scripts associated with HTML pages Process (incoming) network requests from clients/users/web browsers Use HTTP(S) to receive and deliver communications/communicate with clients/web browsers Provide server-side script services/PHP/ASP for dynamic generation of HTML pages. 1(b) Two from: 2 Manage/allow creation of email accounts Host domains for provision of email accounts Send email/outgoing requests using Simple Mail Transfer Protocol/SMTP Receive email/processes incoming mail using Internet Message Access Protocol/IMAP/ Post Office Protocol/POP3. Stores email (messages)/uses store and forward model. 1(c) Two from: 2 Accept print jobs from client computers for printers on a network Manage/direct/allocate print job to appropriate/user defined printer Queue print jobs if allocated printer is busy Allow inspection/management of print queues Allow accounting/charging/quota of print jobs Allow enforcement of admin policies for printing Allow authentication/water-marking of print jobs.

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2 Packet switching is one way of transmitting data between computers in networks. The User Datagram Protocol (UDP) is a protocol used when creating data packets to send to other computers on the network. (a) Explain how the contents of the header are used when sending a data packet using UDP. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [6] (b) Describe the drawbacks of using UDP to send data over a network. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [3]

Mark scheme: 2(a) Six from: 6 Four fields of 2 bytes/16 bits each to hold data about addressing and about the payload data Source port number field used to reply if needed/set to zero if not used/not required Destination port field used to specify receiver address/port number Destination port field is mandatory/always required for delivery purposes (Total) length of packet/header plus data field in bytes used in error checking Length is minimum length of 8 bytes/length of header Checksum field containing results of calculation to check for errors Checksum value is optional in IPv4 but mandatory in IPv6;/set to zero if no value calculated. 2(b) Three from: 3 UDP does not provide acknowledgement of the receipt of a packet so it is deemed unreliable as packets may be lost UDP does provide for ordering of packets so there is no tracking of messages UDP does not provide congestion control so these have to be separately carried out/at application level Recipient must provide mechanisms to address lack of handshake/ordering/duplication of data/messages which increases complexity/overheads.

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3 The process of data mining is divided into phases. Describe the tasks that occur in each of the following phases. (a) business understanding ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [3] (b) data modelling ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [4]

Mark scheme: 3(a) Three from: 3 Identifying the business goals and their impact on the business/organisation Assessing the situation/problem that is to be solved by/what is required from the data mining Defining the goals of the data mining process Producing a project plan. 3(b) Four from: 4 Gathering the data required for the process Documenting/describing the data e.g. location of source/how acquired Listing the source of the data that has been gathered Populate the analysis tool/software with the data Reviewing/exploring the data to check e.g. completeness/anomalies/outliers Visually checking the data for patterns/trends/groupings within the data set(s) Verifying the quality of the data that has been gathered.

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4 Cryptocurrency can be used to make financial transactions. Discuss the impact of the use of cryptocurrency on individuals. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [8]

Mark scheme: 4 Eight from: 8 Positive impacts include: Currency records/transactions are encrypted for security …so privacy/anonymity is assured Not regulated/subject to financial laws …so is not subject to interest rate charges/fees/surcharges during transactions Not subject to exchange rates when used internationally Cannot be seized/’garnished’/frozen as no ownership records are held Offers complete anonymity as there are no (central) records of ownership/transactions Negative impacts include: Transactions are irreversible/cannot be cancelled/be recalled …so if the currency can be sent to the wrong address the value is lost Price/value of currency is not regulated and fluctuates wildly as it is a commodity …so is a high-risk activity Subject to fraudulent claims of high returns for little investment as is a new technology/area of finance Encrypted records of currency hold value but not ownership …so if its stolen/lost there is no proof of ownership so it’s lost Private keys for cryptocurrency can be permanently lost from local storage due to malware/data loss /destruction of/damage to physical media …so cryptocurrency cannot be spent/used/trade resulting …so it is effectively removed from markets Currency can become worthless if markets fluctuate/provider goes out of business/stops trading Some countries do not allow cryptocurrency use …so goods/services cannot be purchased from/in these countries with cryptocurrency. Must be at least two Positives and at least two Negatives for full marks. Max 6 marks if all bullets/statements/points.

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5 A software development company is using the Agile method of software development to create a new app for a client to use on mobile devices. Discuss the use of the Agile method of software development when creating a new app for the client. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [8]

Mark scheme: 5 Eight from: 8 For: Client/customer satisfaction is the highest priority from the earliest stages to the completion of the app development Changes in client/customer requirements can be accommodated at any stage up to final handover of app Agile development produces working/deliverable software for the client in short timescale/early in the development process Developers and users (must) work together throughout development of app to ensure app meets client/customer requirements Face-to-face conversations are often used as most efficient method of fast communication of information/ideas Agile method is deemed to promote/encourage a constant pace of development (indefinitely) so there is no ‘downtime’ waiting for others Errors/mistakes are deduced/corrected quickly as there is constant testing of the app as it is being developed Regular/iterative reviews/testing allows quick correction/alteration of developing software to meet changing demands of client/customer/users leading to technical excellence/good designs Developer teams are allowed to ‘self-organise’ leading to better working practices/designs Against: Requirement for face-to-face/daily communication means that developers have to work is same building/location Design specifications/cost estimates/project plans are not (often) accurate as design changes over time Milestones are difficult to set/recognise as development progresses as developers cannot predict with certainty what they plan to do/create in next week/month/can only predict what e.g. features they will address in near future. Max 6 marks if all bullets/statements/points.

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6 Discuss the advantages and disadvantages of the use of microwave transmissions for communications. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [8]

Mark scheme: 6 Eight from: 8 Advantages: Small/directional antennas point directly at each other …so can use same frequencies as neighbouring transmissions without interference/make economical use of radio spectrum Directional antennae provide increased performance with low power requirements Narrow microwave beams do not interfere with other equipment Small antennae/devices can be used so operations can be mobile e.g. TV sporting transmissions/can be set up quickly to cover unfolding events/can be used in portable radio systems Have large bandwidth …so can carry greater amount of data compared to other media/can carry more radio/telephone channels Disadvantages: High/tall antennae may be environmentally problematic/difficult to install in some areas Line of sight required …so antenna cannot be ’over horizon’/limited to 50 to 80 km apart …so any obstacle will interfere with transmission …so can be interfered with/intercepted Unable to penetrate obstacles/buildings/hills …so positioning of antennas may be intrusive/unsightly Weather/environmental conditions can adversely affect the transmission ‘Rain fade’ due to absorption of microwaves by water can degrade the signals High pollen counts/dust/smoke can degrade signals due to scattering of signals by particles Solar events may affect transmissions/signals so interfere with communications Most of signal passes through antennae so transmissions can be intercepted behind official antenna/in space by satellite so security can be compromised. Must be at least two Advantages and at least two Disadvantages for full marks. Max 6 marks if all bullets/statements/points.

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7 Bitcoin is a decentralised banking system which can be used to buy goods and services. (a) Explain why Bitcoin is classified as a decentralised system. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (b) Describe how Bitcoin can be used to buy goods from another Bitcoin holder. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [4]

Mark scheme: 7(a) Two from: 2 No central bank needed to provide payment services/hold money Payments are made peer-to-peer/direct between persons No central regulatory authority to oversee transactions/financial dealings. 7(b) Four from: 4 Bitcoin wallet/software is set up to provide a Bitcoin address to/from which payments are made Bitcoin addresses are complex number/character sequences staring with a 1 or a 3 Bitcoin(s) are purchased from a Bitcoin exchange and loaded into the wallet Use of credit/debit/bank card/bank transfer only to purchase Bitcoins to store in wallet Bitcoins can be transferred directly from one wallet to another by specifying Bitcoin address of seller to send to Use of Bitcoin debit card that can debit wallet directly when used for payments.

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8 Technology enhanced learning (E-learning) can be delivered using a Massive Open Online Course (MOOC). (a) Describe the features of a MOOC. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [4] (b) Explain the drawbacks to students of using a MOOC. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [4]

Mark scheme: 8(a) Four from: 4 Unlimited/very large numbers of students can participate Unrestricted/open access via the web/internet Can include multimedia/videoed lectures/talks Can include quizzes/interactive tasks for immediate feedback to students Can include online assessments for progress through the MOOC Can include user forums for group discussions. 8(b) Four from: 4 Students who are not digitally literate will not be able to (fully) participate and not make use of the course materials User-generated course materials may devalue/undermine the validity of the course Students who cannot self-motivate/cannot set own goals will not be able to (fully) participate Barriers of language/translations may exclude/restrict/disadvantage some participants from (fully) taking part Very large amounts of content are difficult to navigate/set up/learn/work through without guidance. Practical experience/training is limited/resources for practical work are limited Some students may not be able/be prepared to devote the time and effort necessary/required for the course.

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9 Bit rate is a measure of how fast data can be sent from one device to another on a network. (a) Describe how the bit rate of a video stream is measured on a network. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ............................................................................................................................................. [2] (b) Identify two factors that can affect the bit rate in data communication. 1 ................................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... 2 ................................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... [2]

Mark scheme: 9(a) Two from: 2 Number of bits transmitted/carried/processed per second/unit of time Units are kbps/kilobits per second (Accept other SI/metric/decimal prefixes e.g. megabits per second) Units are 1KiB/s in binary/IS standard (this is 1024 bits/s) (Accept other IEC standard prefixes e.g. 1MiB/s) Candidates might describe how it is physically measured...accept either...e.g.: Start video streaming/play on device/send file of known size Use software to capture video traffic/known file from network (over time period of e.g. several minutes/hour) Select video stream from captured traffic and calculate bits per second. 9(b) Two from: 2 Bandwidth available on the communication channel Level of noise/signal to noise ratio/SNR on the communication channel Number of signal levels used to represent data.

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10 Data stored on a network can be subject to different types of threats. Explain how these threats can be detected. .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .......................................................................................................................................................... .................................................................................................................................................... [6]

Mark scheme: 10 Six from: 6 Use of anti-malware software/anti-virus/anti-spyware to scan incoming data/packets/requests to network Use of anti-malware software/anti-virus/anti-spyware to scan existing on/new files added to network Use of anti-malware software/anti-virus/anti-spyware software to examine signature data from previous/known threats and comparing it to organisation’s data to identify (known) threats Use of firewall to filter packets and block packets identified as containing malicious code Use of proxy servers to hold/use anti-malware software/anti-virus/anti- spyware on requests/incoming data Analyse user actions/behaviour to establish normal/baseline for detection of abnormal/outlier action/behaviour/check what a user normally does/accesses to be able to compare with abnormal accesses by user/check user access times against expected times of access to data Set up traps for intruders that trigger alerts when intruder accesses certain data/’honey trap’ files that are tempting to intruders and then set off alerts for administrators Hunt for threats by examining network traffic/monitor network/user activity to reveal patterns/abnormal activity Analyse network traffic patterns to detect abnormal patterns Gather/analyse user access logs/authentication attempts to discover threats Collect detailed information of malicious events/attacks to provide basis of investigations.

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