19797512
Descripción
Fichas por Ronan Kavanagh, actualizado hace más de 1 año
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Creado por Ronan Kavanagh
hace más de 4 años
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| Pregunta | Respuesta |
| Program | An organised list of instructions that when executed by a computer causes it to perform a specific task. |
| Prototype | A scaled down, working version of the final product meant to: - Test design aspects and features - Illustrate ideas - Get user feedback |
| SDLC Steps | Preliminary Analysis Analysis Design Develop Implementation Evaluation and Maintenance |
| Preliminary Analysis + Example | The project is analysed to see if it is economically viable. Ex: Feasibility study, problem defintion |
| Analysis + Example | The cost and resources of the current system and the ones to be used are analysed Ex: Model of current system, requirements of system |
| Design + Example | The system is designed using charts, diagrams and prototypes. Ex: Creating a GANTT chart, creating a prototype, logical/physical design |
| Develop + Example | The system is developed using the hardware and software required. Ex: Hardware/Software acquisition, construction + testing |
| Implementation + Example | It is decided how the new system will take over the old system Ex: Phased, Pilot, Parallel, Direct Cut |
| Evaluation and Maintenance + Example | Check if the system meets the requirements of the project, preventative maintenance and troubleshooting Ex: Performance evaluation, fault finding + correction |
| Network Topology Types | Star Bus Ring Extended Star |
| Star Network Topology 1 Advantage | All computers connected to a central computer or database. Adv.: If noncentral computer has problems, rest of network still functions |
| Star Network Topology 1 Disadvantage | All computers connected to a central computer or database. Disadv.: If central computer fails, the whole network ceases to function |
| PAN + Example | Personal Area Network: Several different devices connected to a person's personal computer Example: Bluetooth devices connected to laptop |
| LAN + Example | Local Area Network: A network that spans a geographically small area. Example: A group of computers and a server in one room connected in a star topology |
| WiMAX vs WiFi | Worldwide Interoperability for Microwave Access X: . Nodes can cover wider range than WiFi |
| HTTP + How it sends text | Hyper Text Transfer Protocol: Defines how messages are formatted and transmitted and what actions web servers and browsers should take in response to them. Sends in plain text |
| HTTPS + How it sends text | Hyper Text Transfer Protocol: Defines how messages are formatted and transmitted and what actions web servers and browsers should take in response to them. Sends in cipher text |
| Communication Protocols | FTP: File Transfer Protocol HTTP: Hyper Text Transfer Protocol HTTPS: Hyper Text Transfer Protocol Secure SMTP: Simple Mail Transfer Protocol WAP: Wireless Application Protocol TCP: Transmission Control Protocol |
| FTP Definition | File Transfer Protocol: Promotes sharing of files via remote computers with reliable/efficient data transfer. |
| How Does FTP Work? (Hint: 3 points) | - FTP requires user + pass - User computer = Local Host Machine (retrieving files) connects to remote host - Files can be transferred between both hosts |
| Basic Components of a Data Communications System (5 Marks) | Sending device Message (signal) Protocols Receiving device Transmission medium |
| Protocol (2 marks) | - Collection of steps required for two entities to communicate - Separated into logical layers |
| Digital Signal (3 marks) | Distinct on or off pulses. Not continuous Specific values to represent information |
| Analogue Signal (2 marks) | Continual electrical signal in a carrier wave with specific AMPLITUDE and FREQUENCY |
| Ethernet Cable (2 Marks) | Network protocol that accesses the network by first listening to see if the cable is free. Two nodes transmitting at same time is called a collision |
| Bandwidth | The amount of data, instructions and information that can travel over a communication channel |
| Twisted Pair | Two insulated wires twisted around each other to create interference protecting magnetic field |
| Unshielded Twisted Pair + 2 Uses | Twisted core is covered with plastic material without cladding material. LAN network use Low cost |
| Fibre Optic | Made up of one or more thin strands of glass or plastic tubules Uses light signals |
| Benchmark Testing | Performance test of hardware and/or software that uses specific measured indicators (ex: time to render 3D graphics) |
| Rapid Application Developement (RAD) [5 marks] | - Increased speed and quality - Relies on high user involvement - Prototyping - Integrated CASE (computer aided software engineering) tools - Code generators |
| RAD Steps | Initiate: Project setup + preliminary interviews Develop: Develop + Evaluate iterations # Deploy: Review, rebuild and implement |
| JAD | - Users, analysts and managers work together - Specifies and reviews system requirements through intensive meetings |
| Project Management | The set of procedures, rules, technologies and practices that managers use to organise, staff, direct and control a project or system can be delivered ON TIME, IN BUDGET, MEETING REQUIREMENTS of user |
| What is MRIBOT in project management? | Meeting Requirements, In Budget, On Time |
| Insert Anomaly | Data added to poorly constructed table results in data repetition Effect: Increases input error and null value chance |
| Update Anomaly | Same piece of data appears multiple times = Multiple changes needed when updating Effect: If all changes not made, data becomes inconsistent |
| Delete Anomaly | - When an unnormalised table has records holding data on mult. entities - Deleting one record can unintentionally delete other entity information if appears only once |
| Flat File | Single relation Cannot be cross-referenced Cannot be linked |
| Waterfall/Linear SDLC | Each stage occurs serially |
| Linear/Waterfall Pros/Cons | Pros: Not many unforeseen costs, time limits can be achieved, large projects Cons: Difficult to make changes later, if logical/physical flaw found late = costly, takes long time to implement |
| Prototype Pros/Cons | Pros: Allows analyst achieve user requirements better, involves user sooner, reduces user training, cost effective Cons: Unpredictable time/costs |
| Iterative - RAD | Rapid Application Development Gathers system requirements using JAD Constant feedback from users/customers Any quick method |
| JAD | Joint Application Development Intense workshops + focus groups Prototyping + User feedback Re-use of software components (CASE) |
| RAD Pros / Cons | Pros: Faster than SDLC, short dev cycles, flexible to change, meet users need better, feel more comfortable Cons: Lower testing level may be carried out, may be difficult to involve important users |
| OS Definition | Software that makes computer work Co-ordinates all aspects on computer Controls CPU Manages software Can access memory and other devices |
| Role of OS | Scheduling tasks: Task priority and resource allocation Managing concurrency: Simultaneous running decisions Managing memory and addresses Manage devices |
| Types of OS | Embedded Standalone Server |
| Embedded OS [3 Marks] | -Built in to specific hardware config -Designed to be compact and resource efficient + lightweight -Designed to run particular task efficiently |
| Standalone OS [4 Marks] | Works on device by itself Does not require any other library or another OS to boot OS never exits, begins own execution, never fully hands over execution Loads into memory |
| Server OS [2 Marks] | Designed for specific task (usually over network) Has special features required by client-server architecture |
| Role of File Systems [3 Marks] | - Space management - File naming - File directory creation |
| File Names | - Used to identify where specific set of information stored in file system - File name is identifier given to computer file |
| Directories | - Folders = Directories - Capable of grouping specific files to centralised place |
| Database Normalisation Definition + 3 Roles | Breaks down and splits table into smaller ones to: - Implement into relational database - Eliminate redundancy - Organise data efficiently - Reduce potential for data anomalies - Reduce file size (data stored only once) |
| 1st Normal Form Requirements [3 Marks] | - Each table has PK - Each field has atomic value - All repeated fields removed |
| 2nd Normal Form Requirements [4 Marks] | - All 1NF requirements met - Redundant data and separate entities moved to new table - Create/Identify primary keys for new relations - Resulting tables related by foreign key |
| 3rd Normal Form | - Each non-key field functionally dependent on primary key |
| Router | - Communication device that forwards packets from one network to another - Can be used to create subnetworks to balance traffic |
| Gateway | - Entrance to another network - Can be hardware or software - Can translate different protocols (even different types of network can communicate) |
| Firewall | - Filters data coming thru internet connection - Prevents unauthorised user access to private networks - Each message examined and those not meeting criteria blocked |
| Modem | - Converts digital and analogue signals - Can then be transmitted over a telephone line or digitally |
| Repeater | - Extends a network reach - Regenerates signal received |
| Switch | - Connects network segments and devices - Uses MAC addresses to filter/forward traffic to designated device |
| What is Twisted Pair Used For? | Telephone + LAN |
| What is the range of UTP and STP and what is the bitrate? | - 100 metres - 1 Gbps |
| Single Mode vs Multi-Mode Fibre Optic | Single Mode: Single light wave, 3 km Multi-mode: Multiple light waves, 2 km |
| Broadcast Radio Advantages/Disadvantages | - Slower and susceptible to noise than wired + Flexability and portability |
| Microwave Advantages/Disadvantages | + Can have thousands of individual channels - "Line of sight", meaning it relies on repeaters every 30-50 km |
| Satellite Advantages/Disadvantages | + Long distance - Long delay (about 500 ms) |
| Cellular Transmission Def + Advantages/Disadvantages | Network area divided into cells, closest station picks up signal and passes to destination device or station - Radio waves can be intercepted + Low cost, portability |
| CSMA/CD LAN Process (4 marks) | 1. Node "listens" to medium to detect idle state 2. If has data to transmit, transmits to idle medium 3. Stop and wait occurs if collision 4. Random transmission before retransmission |
| CSMA/CA | 1. Node wanting to transmit sends RTS (request to sent) frame 2. If receiving node permits, it sends CTS (clear to send) 3. After CTS received by transmitting node it transmits. Other device sense CTS and do not contest. |
| Point-To-Point Networks | - Dedicated link between two devices - Typically use wired connection example: Two computers communicating via modems |
| Why IPV4 to IPV6 | - Number of addresses possible with 4 octets running out - IPV6 has 6 octets |
| IEEE 802.3 | - Ethernet - Uses wired CSMA/CD - Can be implemented - Divides all data being transmitted into variable length frames |
| IEEE 802.5 | Token passing |
| IEEE 802.3 vs 803.3u vs 803.3z | 802.3 = Ethernet (CSMA/CD) access method 802.3u = Fast ethernet 802.3z = Gigabit ethernet |
| IEEE 802.15 | Bluetooth (point-to-point) |
| SMTP | Simple mail transfer protocol stores and forwards email messages. Messages encrypted using Pretty Good Privacy and Secure Locket Layer. |
| Proxy Server | - Intercepts all requests to a webs server to see if it can fulfil the requests itself (ex. present cached pages) - Forwards to web server if unable to - Saves time + traffic |
| Web Server | - Stores web pages that can be requested by client - Uses HTML and HTTP to format webpages and transfer to client |
| Applications Server | - Holds programs and data that adds functionality to webpages - Example: Feedback forms + database data |
| SAN (4 marks) | - Block based storage area network - Appears as a local disk to client OS - High end servers, disk arrays and mediums - Each server has specific, dedicated access to disk arrays |
| NAS (3 marks) | - Provides file level storage when NAS device installed via TCP/IP - Appears as file server to client OS - Files on NAS can be accessed by workstations and servers |
| Layers of TCP/IP Model | Application Transport Internet Link |
| Application Layer of TCP/IP + Protocols | - Defines protocols that allow user to interact w/ network - Ensures: Data representation, encoding + dialog control - Protocols: HTTP, SMTP, HTTP, FTP, DNS |
| Transport Layer of TCP/IP + Protocols | - Defines how data flows between hosts - Ensures: Reliability, flow control and retransmission Protocols: TCP, UDP |
| Internet Layer of TCP/IP + Protocols | - Defines routing of source packets in internetwork to destination - Ensures: Packet path independent of path and networks taken to get there - Protocols: IPv4, IPv6, ICMP |
| Link Layer of TCP/IP + Protocols | - Defines issues IP packet requires to cross physical link between two devices - Protocols: MAC, PPP, ARP |
| TCP/IP Role | - TCP: Terminating, establishing and maintaining connection - IP: Data transfer, packet addressing, packet routing and fragmentation |
| Parity Checking vs Checksum Byte | Parity Checking: Parity bit added to each coded character Checksum Byte: Checksum byte added to a block transmission (around 500 characters). Uses NACK/ACK. |
| Client Computer | - Communicates with a server computer to access their data and resources |
| Server Computer | - Manages network resources (example: hard disk storage, printer + internet access) |
| "The Internet is decentralised" What does this mean? | - Each host/network connected to the internet is independent |
| Local Carrier | - Provides the "backbone" of the Internet between cities/countries |
| ISP Definition | - Host the servers (Points of Presence) that allow users to connect to the Internet infrastructure placed by local carrier |
| SDLC Data Gathering Techniques | Observation Questionaire Interview Sample forms Sampling volume of work processed by system |
| Standard Operating Environment | - Set of selected software - Installed on all computers on a network within an organisation - All machines have same hardware architecture |
| SOE Pros | - Cost effective and efficient in purchasing and maintaining hardware/software - Network service tasks can be automated, standardised and regulated |
| SOE Cons | - Users may need to adjust to an operating system or software not familiar with - Specialist software sometimes unavailable - Network admin may be needed |
| Role of Drivers | - Software that gives directions to a computer on how to operate a device Example: Installing printer drivers to use printer hardware |
| Virtualisation | - Simulated version of something Example: OS, server, storage device, network resources |
| Platform Virtualisation (2 marks) | - Virtual machine as compact, isolated software container simulating an OS - Other devices, including the VM, sees it as a real computer |
| Virtualisation benefits (4 marks) | - Cost efficient (less hardware, energy efficient) - Faster application/service delivery - VM can be moved to other hardware - Easier backup + better disaster recovery |
| CPU Components | - ALU - Control unit - Registers - Program counter - System Clock - Data, address and control bus |
| ALU | - Performs all arithmetic operations of a CPU such as +, -, multiplication and logic operations (comparisons, <, >) - Used during "Execute" |
| CU | - Control unit extracts instructions from registers and decodes them - Instructs other parts of CPU such as ALU by ensuring decoded instructions are run - Used for "Decode" in Fetch-Execute cycle |
| Registers + Types | - Fastest memory type in a CPU - Instructions called from registers during "Fetch" Instruction Address (Program Counter) Status General |
| Program Counter | - Type of register that contains address for instruction currently being executed - Also counts the sequence of instructions |
| System Clock | - Regulates timing and speed of computer instructions - Uses a vibrating quartz crystal, each pulse a clock cycle - Controls operation of various system buses in computer |
| Fetch-Execute Cycle Steps | 1. Fetch 2. Decode 3. Execute 4. Store |
| Control Bus | - Bus lines used within CPU that allows communication between components - Indicates whether operation is read or write |
| Data Bus | - Two way (read/write) bus lines used by CPU to communicate with other devices - Transfers program instructions to CPU |
| Address Bus | - Specifies the memory address in the device CPU is communicating with |
| Fetch (Fetch-Execute Cycle) | 1. The CU gets address from program counter Instruction fetched from address and stored in instruction register |
| Decode (Fetch-Execute Cycle) | 2. The instruction set is decoded by the control unit so it can be processed (executed) |
| Execute (Fetch-Execute Cycle) | 3. Control unit moves data into ALU registers where arithmetic and logical instructions executed |
| Store (Fetch-Execute Cycle) | 4. The results are written back into primary memory or register by the CU |
| Multi-Processor System | - Computer with multiple processors allowing simultaneous instruction processing - Faster data processing |
| Processing Types | Sequential Parallel Distributed |
| Sequential Processing | - Single task run until completion on single processor - Tasks only completed one at a time |
| Parallel Processing | - Multiple processors w/ program tasks broken up and shared amongst them - CU reassembles results afterwards |
| Distributed Processing | - Multiple processors w/ task broken up and shared amongst them - Uses different types of components (e.g. graphics card) - May be "farmed out" to CPUs in other computers |
| Benchmarking | - Testing the performance of hardware or software by using specific, measured indicators - Enables comparison between similar parts (e.g. processing speed of CPUs) |
| Disaster Recovery Purpose | - Plan that details how to protect computer system during/after a disaster - Specifies how to minimise downtime and data loss |
| Disaster Recovery Tools | Redundant Array of Independent Disks (RAID) Tape Backup (magnetic tape cartridge) CD-RW, DVD-RAM, Blu-Ray |
| Backup Procedures + Explanations | Incremental (Archival): Only files changed since last backup saved Full: Copies and backs up all files in a computer |
| Incremental Backup Pros/Cons | Pros: Fastest method, requires minimal storage space, only most recent changes saved Cons: Recovery time consuming (all incremental backups and last full backup needed) |
| Full Backup Pros/Cons | Pros: Fastest recovery method, All files saved Cons: Longest backup time |
| RAID 0 | - "Striping" is used: Data broken up and spread across disks - One disk used to keep track of data locations (increased speed) - No redundancy (no backup) |
| RAID 1 | - Data duplicated into separate hard disk drive - 100% redundancy - Can survive one disk failure |
| RAID 10 | - Nested/Hybrid RAID - Multiple level one RAIDs in "pairs" Visual: | 1 | 1 | | 2 | 2 | | 3 | 3 | | 4 | 4 | | 5 | 5 | | 6 | 6 | |
| Uninterruptable Power Supply | - Provides emergency power to a comp. system in case of power failure - Gives time for main power source to be activated or for a proper shutdown |
| Desktop Virtualisation | - Servers host entire desktop environment and its' applications specific to each user |
| Personal Computer Virtualisation | - Physical computer runs multiple virtual PCs (with their own OS and applications) - Switching can be done without needing to reboot |
| Server Virtualisation | - Multiple logical servers hosted on one physical computer - Can be used to have many low-power servers on one device (e.g. email, file storage, print) |
| Storage Virtualisation | - Many physical storage devices appear as single logical storage device - Makes it easier to manage data |
| Platform with application virtualisation purpose | - Virtualised applications bring down their own environment on demand, isolated from OS |
| Software License Requirements Types | Network Enterprise Commercial/Proprietary End User License Agreement (EULA) |
| Network | - Can only be installed on certain # of devices - License purchased for every device ("per seat") |
| Enterprise | - Agreement between software dev and organisation - Allows all users to install software on any device unrestricted |
| Commercial/Proprietary | - Licensed under exclusive legal right of copyright holder - Can only be used under certain conditions (cannot modify, further distribute or reverse engineer) |
| EULA | - End user license agreement - Legal contract between manufacturer or author of software and end user - Aims to protect both parties from liability if software is used in unintended way - Details how software can/cannot be used |
| Cloud Computing | - A network of remote servers hosted on Internet rather than local server/personal computer - Can store, manage and process data |
| Distributed Database | - Data broken up + stored across multiple computers across network - Each sites is independent, but sites work together as though combined |
| Centralised Database | - Database and DBMS at same site (all processing done at site) - Can be accessed by terminals connected to site |
| Distributed Database Pros | - Local control over database (e.g. security, hardware) - Not reliant on central site (reduced vulnerability + bottlenecks) - Easy to add other sites - Query processing faster |
| Distributed Database Cons | - Requires complex software/high costs - Harder to manage (more complex) - More processing power used for queries |
| Centralised Database Pros | - Only requires simple DBMS - Easier to manage security + integrity |
| Centralised Database Cons | - Susceptible to bottlenecks - If central database fails, cannot be used - May be difficult to expand |
| Data Warehouse | - Huge database system - Stores and manages data about past and present transactions of an entire business |
| Data Mining | - Using data from a data warehouse to make predictions that may be useful - Finds pattern/relationships amongst data |
| Centralised Database | - DBMS and database at single site (all processing done there) - Data can be accessed remotely via connected terminals |
| Centralised Database Pros | - Only requires simple DBMS - Easier to manage security and integrity (one location) |
| Centralised Database Cons | - If central database fails, cannot be used - Bottlenecks may occur - May be difficult to expand on |
| Distributed Database Pros | - Avoids bottlenecks - Faster query processing - Easy to add different sites |
| Distributed Database Cons | - Requires complex DBMS/Software - Higher cost to run - More difficult to manage - Requires more processing power and maintenance |
| Data Warehouse | - Huge database system - Has data of an entire businesses' past and present transactions - Data can be used for data mining |
| Data Mart | - Subsection of a data warehouse - Relates to specific category of a business (e.g. marketing, sales) - Easy access to frequently needed data |
| Ethical Issues Using Data Warehouses | Privacy Control: Makes it possible to analyse routine of buyers Misinterpretation of Data: Data quality may not be high, correlation vs causation |
| 3 things users tracked by a Data Warehouse should know: | - The purpose of the data collection - How it will be used - Who will be able to mine it and see it - What limits are on the data mining - What securities protect their data - How their data can be collected - Laws that permit government to access it |
| Domain Name System | - Distributed database - Can resolve a hostname (translate domain name into IP address), and if can't asks other DN server |
| Interpreter vs Compiler | Interpreter: Translates source code into machine code line by line as the program runs Compiler: Translates source code in one go before the program runs |
| Syntax Error | - Code syntax is not followed correctly leading to it unable to be executed |
| Logic Error | - Program runs but an error in the algorithm causes an unexpected result to occur |
| Run-Time Error | - While program is running, error causes program to terminate or fail unexpectedly - e.g. trying to divide by 0, datatype mismatch |
| Internal Documentation Examples | - Documentation that makes the program easier to understand for programmers - Example: Comments |
| Modem | - Converts signals between digital and analogue |
| Bridge | - Connects two similar network segments + translates protocols allowing communication |
| Gateway | - Entrance to another network - Can translate protocols allowing different network types to communicate |
| TCP/IP Layers | Application Transport Internet Network |
| Application Layer | - Has protocols that allow user to interact with network Example: Dialog control, data representation |
| Transport Layer | - Has protocols that controls how data flows between hosts Example: Ensures reliability, flow control, retransmission |
| Internet | - Defines the routing packets take to the correct destination |
| Link Layer | - Defines the issues an IP packet requires to cross a physical link between two devices |
| Methods Used to Compromise Network Security | Denial of Service (DoS) Back Doors IP Spoofing Phishing |
| Denial of Service | - Attack tries to consume network/website resources such as CPU, memory, disk space etc. - Continually sending page or login requests can cause this |
| Back Door | - "Back door" created by programmer or hacker is used to bypass security measures |
| IP Spoofing | - Hacker changes the IP address on packet headers to a trusted host - Can be used to gain unauthorised access to a network and can be used for DoS |
| Phishing | - E-mail fraud method where hacker pretends to be legitimate entity - Can be used to extract personal and financial information |
| Cloud Computing Disadvantages | - Cloud servers do not have redundancy and are not backed up - May be bandwidth issues (must be enough servers for devices) |
| Cloud Computing Advantages | - No hardware required (no physical store centre) - Easily accessible (from anywhere) |
| Factors Influencing Performance of Network | Bandwidth Network Design Data Collisions Excess Broadband Traffic |
| Bandwidth effect on Network Performance | - Amount of data that can be transmitted can decreased if network enabling devices fail - Fast or gigabit internet can increase performance |
| Network Design | - Schematic method of showing physical devices/communication lines present When creating networks: - Ability to fulfil required functions (ex: running applications, compatibility) - LAN protocols - Security and cost - Expansion potential |
| Data Collisions | - When two nodes in same network transmit at same time - Packets collide and are fragmented and must be retransmitted - Network segmentation reduces data collisions (using switch or router) |
| Excess Broadcast Traffic | - Causes a slowdown in accessing network services/resources - Consumes bandwidth unnecessarily |
| Referential Integrity | - Ensures foreign keys in one table match primary key in another table - Ensures the link created is active |
| Domain Integrity + Example | - Ensures fields store values of correct type, format and range Data Types: Ensures data is stored in consistent types Field Sizes: Data is stored in most useful and economical way Default Values: Specifies a value that is entered when no explicit value entered |
| Passing Parameters by Value | - The function/module calls a copy of a variable from another function/module - Changing the variable will not change it in its' origin function/module due to it being a copy |
| Passing Parameters by Reference | - Sends a memory reference to the function/module - Ehen it changes it, it changes in the original function/module it was declared in |
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