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Learn about pseudocode, procedural programming, big O notation (constant, linear, polynomial (quadratic), exponential, linearithmic and logartihmic) and the complexity of different data structure, sorting and searching algorithms. Based on the OCR H446 Computer Science A-Level specification. Exam Board: OCR A-Level Specification: Computer Science H446 3.1a - 3.1d - Algorithm Complexity Watch on YouTube : Pseudocode Procedural programming Big O notation Algorithm complexity Pseudocode Pseudocode is a simplified , language-independent way of writing algorithms that looks like programming but uses plain English to describe the steps clearly without worrying about exact syntax . The OCR A-Level Computer Science course uses a form of pseudocode unique to the exam board called 'OCR exam reference language ' that all code in exams will be written in . OCR exam reference language uses closing commands such as endif for an if statement and endwhile for a while loop . It also uses the word then instead of a colon like in Python . YouTube video uploading soon Procedural Language A procedural language , such as Python or Java , is a programming language that structures programs as sequences of step-by-step instructions grouped into procedures or functions . It focuses on breaking tasks into smaller , reusable blocks of code that operate on data , making programs easier to write , understand and maintain . This topic is in both Paper 1 and Paper 2 . YouTube video uploading soon Big O Notation O(n) Big O Notation is a way of describing how the time complexity (how long an algorithm takes ) and space complexity (how much memory it uses ) grows as the size of the input increases . This allows algorithms to be compared in terms of efficiency , using the letter n to refer to the size of the input . Complexity types: Constant - O(1) - The algorithm’s time or space stays the same no matter how large the input is . Linear - O(n) - The time or memory grows directly in proportion to the size of the input . Polynomial - O(n²) - The growth increases in proportion to the square of the input , often seen in algorithms with nested loops . Exponential - O(2ⁿ) - The time or memory doubles with each additional input element , becoming extremely slow very quickly . Logarithmic - O(log n) - The algorithm’s time grows very slowly as the input size increases , often achieved by repeatedly halving the data . Linearithmic - O(n log n) - A combination of linear and logarithmic behaviour, common in efficient sorting algorithms like merge sort . YouTube video uploading soon Algorithm Complexity Best-case , average-case and worst-case complexity describe how an algorithm performs under different input conditions . Best-case complexity is the time or space required when the algorithm meets the most favourable input , allowing it to finish as quickly or efficiently as possible . Average-case complexity represents the expected performance across typical or random inputs , giving a realistic view of how the algorithm behaves in normal use . Worst-case complexity is the maximum time or space the algorithm could ever require , used to guarantee performance even in the least favourable situation . Sorting and searching algorithms often have different case complexities for time and space . YouTube video uploading soon This page is under active development. Check here for the latest progress update. Q uesto's K ey T erms Pseudocode Procedural Language: input, output, comments, variables, casting, count-controlled iteration, condition-controlled iteration, logical operators, selection, string handling, subroutines, arrays, files Big O Notation: time complexity, space complexity, constant, linear, polynomial, exponential, logarithmic, linearithmic, best-case, average-case, worst-case D id Y ou K now? Minecraft doesn’t load the entire world at once ; instead, it divides the world into chunks and only generates or loads the chunks near the player . Finding , saving and retrieving these chunks uses data structures like trees and hash maps , which allow the game to look up a chunk in about O(log n) or even O(1) time , minimising lag even in large worlds . 2.2 - Computational Methods A-Level Topics 3.1e - Data Structure Algorithms

Learn about how information can be classified into groups including private, public, sensitive and confidential. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 2.2 - Information Classification Exam Board: OCR Specification: 2016 - Unit 2 Information can be classified into different groups . Some data may fall into more than one classification. Sensitive Information Description: Information that should be protected from being publicly released as it could harm the safety or privacy of an organisation or an individual . Examples: Medical data that could be embarrassing to an individual if released. Financial data that will negatively impact the company if made public to competitors. Non-Sensitive Information Description: Information that can be released publicly with no fear of negative consequence . Examples: Store information including shop addresses , opening hours and the names of senior managers. Product information including prices , online reviews and general availability . Private Information Description: Private information relates to an individual and it should not be shared with anyone else without the data subject's permission . Private information is protected by the Data Protection Act and would need to be stored securely so it cannot be accessed without authorisation. Examples: Home addresses, contact information, birth dates and banking details . Employee data such as linked bank accounts and addresses. Public Information Description: Released to the public and can therefore be seen by anyone . Public information is non-sensitive . Examples: Social media usernames, posts and shared images. Public business information including addresses, promotional material and opening times. A government report like the national census every ten years. Personal Information Description: Identifiable data about a specific individual . Examples: Full name , date of birth , gender , marital status, medical history, sexual orientation and voting history. Business Information Description: Any kind of data about a specific business. This information could be public or private. Examples: Address of its headquarters Financial data or employee details. Annual sales figures . Confidential Information Description: Private data that is more restricted than sensitive information , with access limited to only those who need to know. Examples: Doctor / therapist notes Business Profits and losses Trade secrets Classified Information Description: Highly sensitive information stored by a government institution , requiring the highest levels of restricted access . Access is usually restricted by law and only viewable by authorised individuals or groups. In the UK there are three levels of classified information: OFFICIAL , SECRET and TOP SECRET . Examples: Military data Terrorism precautions Crime scene reports Anonymised Information Description: Anonymisation removes personally identifiable data from information so that an individual cannot be identified . This allows the information to be used in much wider context without running the risk of legal action. Examples: Partially anonymised information - where some of the personal information has been removed and replaced by a symbol . Completely anonymised information - where all identifiable data has been removed . Bank details are often partially or completely anonymised. A partially anonymised credit card number might be listed as: **** - **** - **** - 7427 Problems with anonymising data include: If sensitive data is not anonymised enough and the person can be identified . Useful information could be lost if too much data is anonymised . The public could lose trust in an organisation if data is insufficiently anonymised . Q uesto's Q uestions 2.2 - Information Classification: 1. Describe each type of information classification and give at least two examples : a. Sensitive information [3 ] b. Non-Sensitive information [3 ] c. Private information [3 ] d. Public information [3 ] e. Business information [3 ] f. Confidential information [3 ] g. Classified information [3 ] h. Anonymised information (partial and complete) [6 ] 2. State which classification(s) the following pieces of information would be categorised as. It might fit into more than one category. a. Shop opening times [1 ] b. Medical history [1 ] c. Twitter username [1 ] d. Crime scene report [1 ] 3. Describe three problems that organisations should consider when anonymising data . [6 ] 2.1 - Information Styles Topic List 2.3 - Quality of Information

Learn how to create more HTML pages and link them together using the anchor tag. 10. More Pages HTML Guide Watch on YouTube: Create a New Page Create a new page by either clicking the new page icon in Notepad ++ or selecting File then New . Then you need to save your new page with an appropriate name as a HTML file . Create a new page, save it and add information to it. Your new page needs the same essential tags as your original page: Then you can add the rest of your content . Link to Other Pages The tag is used to link between pages , just like it is used to hyperlink to other websites. Make sure you type your web pages exactly as you have saved them. Make sure all of your web pages are saved in the same folder . Include links between pages on each new page. A link to the second page. Don't forget a link back to your homepage on each new page. Why not add more pages to make your website more detailed? 9. Colours & Fonts HTML Guide

Learn about project planning tools such as the Arrow diagram, Critical Path Analysis (CPA)/Critical Path Method (CPM), Flowcharts, Gantt charts, PERT charts and SWOT (Strengths / Weaknesses / Opportunities / Threats) analysis. Based on Unit F160 (Fundamentals of Application Development) for the OCR Cambridge Advanced National in Computing (H029 / H129) (AAQ - Alternative Academic Qualification). Qualification: Cambridge Advanced National in Computing (AAQ) Unit: F160: Fundamentals of Application Development Certificate: Computing: Application Development (H029 / H129) 3.2 - Project Planning Tools Watch on YouTube : Project planning tools Arrow diagram Critical path analysis Flowcharts Gantt charts PERT charts SWOT analysis Project Planning Tools Project planning tools help to visualise the project by clearly showing tasks , timelines and dependencies . They also break down complex work into smaller , manageable steps and can be used to track progress and identify delays . Each tool suits different project needs and has its own advantages and disadvantages . Choosing the right tool makes planning more accurate , efficient and successful . Arrow Diagram The arrow diagram method is a project planning tool that represents tasks as arrows connected in sequence to show their order and dependencies . It helps identify the critical path . This is the longest sequence of dependent tasks that determines the project’s minimum completion time . This method is useful for visualising task relationships , spotting bottlenecks and showing the order of activities . Critical Path Analysis Critical path analysis ( CPA ), also known as the critical path method ( CPM ), is a project planning tool used to identify the critical path . This is the sequence of tasks that determines the shortest possible project duration . It highlights tasks that cannot be delayed without affecting the overall timeline . Critical path analysis helps prioritise resources , manage dependencies and minimise project delays . Flowcharts A flowchart is a diagram that represents a process or workflow using standard symbols and arrows to show the sequence of steps . It helps visualise decision points and actions and clearly highlights the flow of information or tasks . Flowcharts make complex processes easier to understand , communicate ideas to clients and troubleshoot potential problems . Gantt Charts A Gantt chart is a visual project management tool that displays tasks along a timeline , showing their start and end dates . It helps track task dependencies , overlaps and progress at a glance . Gantt charts are useful for coordinating work , meeting deadlines and ensuring all project stages are completed in order . PERT Charts A PERT ( program evaluation and review technique ) chart is a project planning tool that maps tasks , their dependencies and timelines in a network diagram . It uses three time estimates ( optimistic , most likely and pessimistic ) to calculate expected completion times for each task . PERT charts are especially useful for scheduling complex projects and identifying the critical path to meet deadlines . SWOT Analysis SWOT analysis is a strategic planning tool used to identify a project’s strengths , weaknesses , opportunities and threats . Strengths and weaknesses focus on internal factors ( controllable by the organisation ), while opportunities and threats look at external influences ( outside of the organisation's control ). It helps guide decision-making by highlighting advantages , weaknesses to address and potential risks or openings in the wider environment . Q uesto's Q uestions 3.2 - Project Planning Tools: 1. Define the term 'critical path ' and explain why it is calculated . [3 ] 2. Explain the S , W , O and T in SWOT analysis (not just what they stand for). [4 ] 3. Choose three project planning tools and describe the advantages and disadvantages of each . [ 12 ] Henry Gantt , an American engineer , created the Gantt chart in the 1910s . It has been used as a planning tool in many major projects , including building the Hoover Dam . D id Y ou K now? 3.1 - Planning Projects Topic List 4.1 - Gathering Client Requirements

Learn about the importance of testing applications, test plan structure, test types and test data. Resources based on Unit F161 (Developing Application Software) for the OCR Cambridge Advanced Nationals in Computing (H029 / H129) AAQ (Alternative Academic Qualification). Qualification: Cambridge Advanced Nationals in Computing (AAQ) Certificate: Computing: Application Development (H029 / H129) Unit: F161: Developing Application Software 5.1 - Testing Watch on YouTube : Purpose of testing Test plan structure Test data Types of testing You need to know the purpose , importance , advantages and disadvantages of testing applications , as well as the impacts of not carrying out testing . You must understand the structure and contents of test plans and the importance of testing , remedial actions and retesting during application development. You need to know the role of each type of test data (normal , extreme and erroneous ). Finally, the purpose , advantages and disadvantages of each type of testing (technical and user ) must be known as well as when and how each type should take place . What You Need to Know Purpose of Testing ? YouTube video uploading soon Test Plan Structure ? YouTube video uploading soon Types of Test Data ? YouTube video uploading soon Types of Testing ? YouTube video uploading soon Q uesto's Q uestions 5.1 - Testing: 1. What? [2 ] 2. What? [1 ] 3. What? [1 ] 4. What? [1 ] ? D id Y ou K now? 4.1 - Security Considerations Topic List 5.2 - Application Installation

Learn about the purpose of Green IT, the benefits for an organisation following its practice and methods of use. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification for Unit 2 (Global Information). 4.3 - Green IT Exam Board: OCR Specification: 2016 - Unit 2 What is 'Green IT'? ‘Green IT ’ is to use computers and IT resources in an efficient and environmentally responsible way to reduce an organisation’s carbon footprint . To 'reduce carbon footprint ' means to decrease the amount of pollution (such as CO2 ) produced by an organisation and to engage in more eco-friendly practice. Examples of Green IT Practice Global Requirements of Green IT United Nations Climate Change conferences occur every year and are attended by leaders of each country in the United Nations. The conferences establish obligations for countries to work towards reducing their carbon footprints and emissions of greenhouse gases . Whilst Green IT is not specifically mentioned in these talks, IT is a hugely important sector with large annual emissions that need to be reduced to meet the climate change limitations, such as the Paris Agreement. In the UK, the Greening Government ICT Strategy (running between 2011 and 2015) was an annual report that investigated how IT use could become 'greener' within the government . Positive consequences of this strategy included: Using more cloud storage technology , enabling fewer individual storage devices to be purchased, reducing emissions . Using social media more widely to contact voters - saving money by posting fewer letters and leaflets. Increasing the use of teleconferencing and video calls - reducing the need for unnecessary travel to meetings and avoiding the generation of heavy pollution. Q uesto's Q uestions 4.3 - Green IT: 1. What is meant by the term 'Green IT '. [3 ] 2a. Explain four ways that an organisation can follow good green IT practice . [4 ] 2b. Describe two reasons why it is beneficial to a company of following Green IT . [4 ] 3a. Why are the United Nations Climate Change conferences important ? [2 ] 3b. Describe two ways that the UK government have used Green IT . [4 ] Turn off computers , monitors and other connected devices when not in use . Adjust power options to help minimise power consumption. Use cloud storage or virtualisation to reduce the number of physical devices being bought, powered and maintained. Repair older devices rather than throwing them away. Consider if it is necessary to print a document before doing so and print only what is required . Recycle ink cartridges and paper . Donate older equipment to charities or schools for reuse . Why use Green IT? It is in an organisation's best interests to use Green IT practices for the following reasons: To become more sustainable by reducing the company's carbon footprint and positively impacting the environment . Reducing energy costs (e.g. by turning equipment off when not in use) and saving money . Improving the public image of the organisation as people are increasingly environmentally conscious and will prefer to do business with a company that follows environmentally-friendly policies. 4.2 - Global Legislation Topic List 5.1 - Data Types & Sources

Learn about the advantages and disadvantages of different types of software including open-source, closed-source, off-the-shelf and bespoke. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification. 2.1: Software Types Exam Board: OCR Specification: 2016 - Unit 1 Software refers to the programs and applications that run on a computer system. Open Source Software Source code is the software code written by programmers . If the software is open source it means that users can view and modify the code . Linux, Python and Firefox are examples of open source software. Benefits Drawbacks Because the source code is available to edit , it can be customised to the organisation's needs . Often shared in the public domain so users can work together to modify, debug and improve a product. Unwanted features can be removed to make the software run faster . There are security risks - some editors may add malicious code to the program. Open source software is often low in price and sometimes free. It may be difficult to receive support as development is often distributed between people in different locations. The code may be prone to errors as it may not have been tested fully. It requires technical skills to be able to adapt source code efficiently and to maintain the code . Closed Source Software If the software is closed source it means the code is restricted for users to view or modify . You buy the right to use the software but you don't actually own it. Microsoft Office, Fortnite and Spotify are examples of closed source software. Closed source software is also known as proprietary software because it is another company's property and protected by law. Benefits Drawbacks The code is well tested and has been professionally developed. Updates will generally be secure . Users must rely on the company to provide updates and fix issues. This might be infrequent or stop completely. The company can be held to account if it does not perform as listed in the terms and conditions upon purchase. Often not free (see Freeware below for free closed source software). Most developers will provide some form of help/support . Users cannot modify, debug or improve the code for their own benefit. Off-the-Shelf Software This is any software made for general use , with features that can be used in different ways and for different purposes . Examples include office software (e.g. Microsoft Office), video games (e.g. Minecraft) and image editors (e.g. Adobe PhotoShop). Back before internet downloads, people had to actually go to shops and buy software off the shelf and install it at home, hence the name. Benefits Drawbacks Should have been tested thoroughly so users can be confident that features will work as expected . Secure updates will be regular. It can be expensive to purchase some software , especially for a single user rather than a business. Some software, such as anti-virus protection, requires yearly licenses . It can be cheaper to purchase than bespoke software as it is not customised for a specific user or organisation. The software may contain additional features that the user / organisation doesn’t need which can reduce the performance of the system. The end users might be familiar with the software and trust the company (e.g. Microsoft Word). Bespoke Software This is any software that has been custom made for a specific organisation or user. For example, programmers might be hired by a company to create software for a specific task. Hospitals and schools use bespoke software to track and manage patients / students. It can be expensive to commission bespoke software as programmers and user interface designers need to be hired and there could be issues with rights to any created software. Benefits Drawbacks The software is built to the company's requirements , it is unique to their needs. Unwanted features can be removed to make the software run faster . Bespoke software is expensive to develop because it is tailor-made for the company. Staff may require training on using the system because it is unique . The look of the software (e.g. design & layout ) can be customised to fit the company's image. Because it has been custom-made, the original programmers may be needed to maintain the software and fix errors . Shareware This software allows the user to trial the program for a limited time before forcing them to buy the product or stop using it. For example, WinRAR is utility software that asks the user to buy the full version after 40 days. This allows the user to get a taste of what the software offers before choosing whether to buy it fully or not . Freeware This is software that is freely available to download and use . These are usually closed-source software that earn money through adverts or additional purchases. Rights to the software remain with the author despite the free access. App developers may release their app as freeware to allow users to try the software and then encourage them to purchase a full version with more features. Unlike shareware, the user should be able to keep using the product for free indefinitely, though their version may have features restricted or adverts enabled. Examples of freeware software include iTunes , Clash of Clans and Adobe Acrobat Reader (for PDFs). Embedded Software An embedded system is when a smaller computer system is installed within a larger device , such as a washing machine, traffic light or car. Embedded systems have a dedicated purpose and often run in real-time . Because of the small size, the embedded software will usually have memory and storage restrictions . Q uesto's Q uestions 2.1 - Software Types: 1. Describe the 7 types of software , listing the advantages and disadvantages of each. a. Open Source b. Closed Source c. Off-the-Shelf d. Bespoke e. Shareware f. Freeware g. Embedded [6 each ] 1.8 & 1.9 - Number Systems Topic List 2.2 - Applications Software

Learn about how to convert between the denary (decimal), binary and hexadecimal number systems. Based on the 2020 Eduqas (WJEC) GCSE specification. 4.1: Number Systems Exam Board: Eduqas Specification: 2020 What is binary? By now you should know that computer systems process data and communicate entirely in binary . Topic 1.4 explained different binary storage units such as bits (a single 0 or 1), nibbles (4 bits) and bytes (8 bits). Binary is a base 2 number system. This means that it only has 2 possible values - 0 or 1 . Because binary is a base 2 number system, binary numbers should be written out with a 2 after them, like this: 10101002 What is denary? Denary (also known as decimal ) is the number system that you've been using since primary school. Denary is a base 10 number system. This means that it has 10 possible values - 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 . Because denary is a base 10 number system, denary numbers should be written out with a 10 after them, like this: 165 10 How to convert from binary to denary: How to convert from denary to binary: What is hexadecimal? Hexadecimal is a base 16 number system. This means that it has 16 possible values - 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E and F . Because hexadecimal is a base 16 number system, hexadecimal numbers should be written out with a 16 after them, like this: 6E16 Hexadecimal is used as a shorthand for binary because it uses fewer characters to write the same value . This makes hexadecimal less prone to errors when reading or writing it , compared to binary. For example, 1001111010112 is 9EB16 . Hexadecimal only uses single-character values. Double-digit numbers are converted into letters - use the table on the right to help you understand. How to convert from binary to hexadecimal: How to convert from hexadecimal to binary: Converting from denary to hexadecimal / hexadecimal to denary To convert from denary to hexadecimal or the other way round you must convert to binary first . Denary > Binary > Hexadecimal Hexadecimal > Binary > Denary Use the videos on this page if you need help converting to or from binary. The most common number systems question in exams are from denary to hexadecimal or from hexadecimal to denary so make sure that you practice these conversions. Q uesto's Q uestions 4.1 - Number Systems: 1. Explain why hexadecimal numbers are used as an alternative to binary . Use an example . [ 3 ] 2. Convert the following values from binary to denary : a. 00101010 2 b. 11011011 2 c. 01011101 2 d. 11101110 2 e. 01011111 2 [1 each ] 3. Convert the following values from denary to binary : a. 35 10 b. 79 10 c. 101 10 d. 203 10 e. 250 10 [1 each ] 4. Convert the following values from binary to hexadecimal : a. 11110101 2 b. 01100111 2 c. 10111010 2 d. 10010000 2 e. 11101001 2 [1 each ] 5. Convert the following values from hexadecimal to binary : a. C2 16 b. 8A 16 c. DE 16 d. 54 16 e. F7 16 [1 each ] 6. Convert the following values from denary to hexadecimal : a. 134 10 b. 201 10 c. 57 10 d. 224 10 e. 101 10 [1 each ] 7. Convert the following values from hexadecimal to denary : a. 32 16 b. A5 16 c. 88 16 d. C0 16 e. BE 16 [1 each ] Watch on YouTube Watch on YouTube Watch on YouTube Watch on YouTube Click the banners above to try self-marking quizzes (Google Form) on these topics. Denary to Binary: Binary to Denary: Binary to Hexadecimal: Hexadecimal to Binary: 3.9 Protection Against Threats Theory Topics 4.2 - Signed Binary

Learn about different types of hardware that allow data to be sent between systems, including router, modem, bridge and WAP. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification. 1.5: Communication Hardware Exam Board: OCR Specification: 2016 - Unit 1 The devices on this page are used to create or link together networks , allowing data to be sent between computer systems . Hub A hub receives data packets from a connected device and transfers a copy to all connected nodes . Switch A switch receives data packets , processes them and transfers them on to the device s pecifically listed in the destination address of the packet. Modem Modems are used to send data across the telephone network . The telephone lines can only transfer analog signals so a modem is used to convert a computer's digital data into an analog signal . Another modem converts the signal back to a digital format at the receiving end. Router Routers are used to transfer data packets between networks . Data is sent from network to network on the internet towards the destination address listed in the data packet. A router stores the address of each computer on the network and uses routing tables to calculate the quickest and shortest path . Wireless Access Point (WAP) Provides a link between wireless and wired networks . It creates a wireless local area network that allows WiFi enabled devices to connect to a wired network. Combined Device Also known as a hybrid device , this provides the functionality of multiple communication devices (e.g modem, router, switch and/or wireless access point) in a single device . They can be more expensive than a single device but are more adaptable - if the routing part of the device fails it might still be able to function as a switch / wireless access point etc. However, you will see an increased performance from a standalone device rather than a combined one as standalone devices have more complex features (e.g. VPN support). Network Interface Card (Network Adapter) A Network Interface Card (often shorted to NIC ) is an internal piece of hardware that is required for the computer to connect to a network . It used to be a separate expansion card but now it is commonly built directly into the motherboard (and known as a network adapter ). Wireless network interface cards allow wireless network connection. Q uesto's Q uestions 1.5 - Communication Hardware: 1. What is the difference between a hub and a switch ? [2 ] 2. Explain how a modem works. [3 ] 3. Explain the purpose of a router . [2 ] 4. What is a Wireless Access Point (WAP )? [2 ] 5. Describe what is meant by a 'combined device '. Give one advantage and one disadvantage of using a combined device. [3 ] 1.4 - Connectivity 1.6 - Hardware Troubleshooting Topic List

Learn about digital methods of protecting data such as anti-malware, firewall, usernames and passwords, levels of access and encryption. Based on the 2016 OCR Cambridge Technicals Level 3 IT specification. 5.5 - Digital Security Exam Board: OCR Specification: 2016 - Unit 1 ****** Usernames & Passwords Usernames must be matched with a secure password to minimise the chances of unauthorised users accessing a system. Passwords should contain a mix of uppercase and lowercase letters , punctuation and numbers . Passwords should be of a substantial length (at least 8 characters) and should be regularly changed . Digital Security Measures Firewall Firewalls (see 2.3 ) prevent unauthorised access to or from a network . Firewalls filter data packets and block anything that is identified as harmful to the computer system or network. Firewalls can also be used to block access to specific websites and programs. Encryption Encryption is the conversion of data ( plaintext ) into an unreadable format ( ciphertext ) so it cannot be understood if intercepted . Encrypted data can only be understood by an authorised system with a decryption key . Anti-Malware Anti-virus software (see 2.3 ) scans a system and removes viruses . If left to infect a system a virus could delete data or permit access to unauthorised users . Anti-spyware software removes spyware on an infected system so hackers cannot view personal data or monitor users. Organisations should install and regularly update anti-virus and anti-spyware programs. Permissions Permissions is the creation of different levels of file access so that only authorised people can access and change certain files . There are different levels of file access : No access Read-only Read/write Q uesto's Q uestions 5.5 - Digital Security: 1a. Describe why usernames and strong passwords are necessary. [2 ] 1b. State 3 rules for choosing a strong password . [3 ] 2. Describe the purpose of anti-virus and anti-spyware software. [4 ] 3. Describe the roles of a firewall . [4 ] 4. Explain what encryption is. [3 ] 5. What are permissions ? What are the 3 levels of access ? [5 ] 5.4 - Physical Security Topic List 5.6 - Data & System Disposal

Learn about the six parts of a data packet and how packet switching works. Based on the 2020 Eduqas (WJEC) GCSE specification. 3.2: Data Packets & Switching Exam Board: Eduqas Specification: 2020 What is a data packet? When sending data across a network, files are broken down into smaller parts called data packets . Whole files are too large to transfer as one unit so data packets allow data to be transferred across a network quickly . Each packet of data is redirected by routers across networks until it arrives at its destination. Data packets may split up and use alternative routes to reach the destination address. When all the packets have arrived at the destination address the data is reassembled back into the original file. Contents of a Data Packet Data packets contain six distinct pieces of data which are used to redirect the packets towards the destination address. Packet Switching vs. Circuit Switching The key difference is that a circuit-switched network sends data along the same route . A packet-switched network sends data packets along different routes . Packet Switching With a packet-switched network the data is split into packets . The data packets are transmitted over a network and may take different routes to its destination. When all the packets have arrived the data is reassembled . The Internet is an example of a packet-switching network. Advantages of Packet Switching: Transmission is more secure as it is harder for a hacker to intercept complete data because it can take different routes . If a network device fails the data packets can take an alternative route . Data packets can be sent efficiently and individually across less busy routes . Disadvantages of Packet Switching: Reassembling the data takes longer because packets may arrive out of order . It is less reliable than circuit switching as some data packets may not reach the destination (this is called packet loss ). Circuit Switching When data is transmitted over a circuit-switched network all of the data takes the same route to the destination address in one continuous stream . The data is quickly reassembled at the destination because it is already in the correct order . The old telephone system is an example of a circuit-switched network. Advantages of Circuit Switching: Reassembling the data is quick because the packets arrive in the order that they were sent. It is more reliable than packet-switching because data is sent in one continuous stream . The transmission is fast and should encounter fewer errors - once the connection has been securely established . Disadvantages of Circuit Switching: Less secure as hackers could intercept the data and more easily access the data as it all takes the same route. Establishing a connection takes time to set up. If any device fails on the route then the whole connection breaks and data transfer will be incomplete. Q uesto's Q uestions 3.2 - Data Packets & Switching: 1. Draw the data packet diagram and label all 6 pieces of information . [ 6 ] 2a. Describe how packet switching works . [3 ] 2b. Describe the advantages of packet switching . [3 ] 2c. Describe the disadvantages of packet switching . [2 ] 3a. Describe how circuit switching works . [3 ] 3b. Describe the advantages of circuit switching . [3 ] 3c. Describe the disadvantages of circuit switching . [3 ] 3.1 - Network Characteristics Theory Topics 3.3 - Network Topology

Learn about six network devices - hub, switch, router, bridge, WAP and NIC. Also, learn about routing tables and cost diagrams. Based on the 2020 Eduqas (WJEC) GCSE specification. 3.4: Network Hardware & Routing Exam Board: Eduqas Specification: 2020 Network Devices Hub A hub receives data packets from a connected device and transfers a copy to all connected nodes . Switch A switch receives data packets , processes them and transfers them on to the device specifically listed in the destination address of the packet. Router Routers are used to transfer data packets between networks . Data is sent from network to network on the internet towards the destination address listed in the data packet. A router stores the address of each computer on the network and uses routing tables to calculate the quickest and shortest path . Bridge A bridge joins together two networks that use the same base protocols . For example, a bridge could link together a LAN to another LAN . Wireless Access Point (WAP) Provides a link between wireless and wired networks . It creates a wireless local area network that allows WiFi enabled devices to connect to a wired network. Network Interface Card (NIC) A Network Interface Card (often shortened to NIC ) is an internal piece of hardware that is required for the computer to connect to a network . It used to be a separate expansion card but now it is commonly built directly into the motherboard (and sometimes known as a network adapter ). Wireless network interface cards ( WNIC ) permit a wireless network connection. Routing A routing table is a list of the optimal routes for data packets to be sent from one device to another. Routing tables should be kept accurate and up to date to ensure that packets are transferred as quickly as possible . During routing the lowest cost route is calculated . This is the shortest path with the fastest nodes to transfer data. Below is a simplified network and basic routing table showing the lowest cost (optimal) route using node A as the source address. Q uesto's Q uestions 3.4 - Network Hardware & Routing: 1a. Describe the difference between a hub and a switch . [ 2 ] 1b. Explain how a modem works. [ 2 ] 1c. Describe the purpose of a router . [ 2 ] 1d. Describe the difference between a gateway and a bridge . [ 2 ] 1e. State what WAP stands for and describe its purpose . [ 2 ] 1f. State what NIC stands for and why it is required . [ 2 ] 2a. Describe what a routing table is and why they should be maintained . [ 2 ] 2b. In terms of routing, what does a low-cost route mean? [ 2 ] 2c. Copy and complete the routing table below using node J as the source address . [ 4 ] 3.3 - Network Topology Theory Topics 3.5 - Protocols