KASNEB DICT cheat sheet

1 byte = 8 bits; 1 KB = 1,024 bytes; 1 MB = 1,024 KB; 1 GB = 1,024 MB.

Data are raw facts; information is processed data that supports decisions; knowledge is information combined with experience and context.

A spreadsheet formula always begins with '='; relative references (A1) shift when copied, absolute references ($A$1) do not.

Common spreadsheet functions: =SUM(range), =AVERAGE(range), =IF(condition, value_if_true, value_if_false), =COUNT, =MAX, =MIN.

Mail merge = main document + data source; it produces one personalised copy of the document per record in the data source.

Chart selection rule: pie for parts of a whole, line for trends over time, column/bar for comparing categories.

The slide master controls fonts, colours and layout for all slides; transitions occur between slides, animations occur within a slide.

Computer size classes in descending order: supercomputer, mainframe, minicomputer, microcomputer (PC).

Components of an ICT system: hardware, software, data, people, procedures and connectivity.

CPU = Control Unit + ALU + registers; the control unit fetches and decodes instructions, the ALU performs arithmetic and logic operations.

Instruction cycle: fetch, decode, execute, store; clock speed in GHz gives the number of cycles per second.

RAM is volatile and holds the program and data currently in use; ROM is non-volatile and holds firmware such as the BIOS.

Cache hierarchy: L1 (smallest and fastest), then L2, L3, then RAM; SRAM is used for cache, DRAM for main memory.

An address bus of width n limits memory to 2^n addressable locations; data bus width sets the number of bits transferred per cycle.

HDD stores data magnetically on rotating platters; SSD stores data in flash memory and has no moving parts, giving faster access.

The motherboard carries the CPU socket, chipset, memory slots, expansion slots (PCIe) and firmware (BIOS/UEFI).

Printer types: laser uses toner and a drum, inkjet uses liquid ink, dot-matrix is impact-based and can produce carbon copies.

Ports: USB (universal serial), HDMI (digital audio and video), VGA (analogue video), RJ-45 (Ethernet), 3.5 mm audio jack.

Core OS functions: process management, memory management, file management, device/IO management, security and the user interface.

OS categories: batch, multiprogramming, multitasking, time-sharing, real-time, distributed and embedded.

CPU scheduling algorithms: FCFS, shortest job first, priority scheduling and round robin (fixed time slice).

Four necessary conditions for deadlock: mutual exclusion, hold and wait, no pre-emption and circular wait; removing any one prevents deadlock.

Paging divides memory into fixed-size pages and frames; virtual memory uses disk as an extension of RAM; excessive page swapping is thrashing.

File systems: FAT32 (4 GB maximum file size, no permissions), NTFS (permissions, journaling, encryption), ext4 (Linux).

Boot sequence: power-on, POST, BIOS/UEFI, boot loader, OS kernel, user login.

Utility programs: disk defragmentation (HDD only), disk cleanup, backup, antivirus, file compression and task manager.

Preventive maintenance: dust removal, driver and firmware updates, UPS and surge protection, scheduled backups and disk error checking.

OSI layers from 1 to 7: Physical, Data Link, Network, Transport, Session, Presentation, Application.

TCP/IP model layers: Network Access, Internet, Transport and Application.

Device-to-layer mapping: hub and repeater = layer 1, switch and bridge = layer 2, router = layer 3, gateway = up to layer 7.

IP address classes: A 1-126, B 128-191, C 192-223, D 224-239 (multicast), E 240-255 (experimental).

Private address ranges: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16; loopback address is 127.0.0.1.

Prefix /24 equals mask 255.255.255.0 and gives 254 usable hosts; usable hosts = 2^h - 2 where h is the number of host bits.

Common ports: HTTP 80, HTTPS 443, FTP 20/21, SSH 22, Telnet 23, SMTP 25, DNS 53, DHCP 67/68, POP3 110, IMAP 143.

Topology rules: star allows easy fault isolation but has a central point of failure; mesh gives the highest redundancy; bus uses one shared backbone.

Guided media: twisted pair (UTP/STP), coaxial cable and fibre optic (immune to EMI, highest bandwidth); unguided media: radio, microwave, infrared.

Program development steps: problem definition, analysis, design, coding, testing, implementation and maintenance.

Flowchart symbols: oval = start/end, parallelogram = input/output, rectangle = process, diamond = decision, arrow = flow of control.

Three control structures: sequence, selection (IF/ELSE, CASE) and iteration (FOR, WHILE, DO...WHILE).

Language generations: 1GL machine code, 2GL assembly, 3GL high-level procedural (C, Pascal), 4GL non-procedural (SQL), 5GL artificial intelligence/declarative.

A compiler translates the whole source program before execution; an interpreter translates and executes one statement at a time.

Testing levels in order: unit, integration, system, acceptance (UAT); black-box testing uses inputs and outputs only, white-box testing uses code structure.

Parameter passing by value copies the argument so the original is unchanged; by reference passes the address so the original can be altered.

OOP pillars: encapsulation, inheritance, polymorphism and abstraction.

Variable scope: local variables are declared inside a block and are not visible outside it; global variables are declared outside and are visible throughout.

Relational terms: relation = table, tuple = row/record, attribute = column/field, degree = number of attributes, cardinality = number of tuples.

Keys: a superkey contains a candidate key; one candidate key is chosen as primary key; a foreign key references the primary key of another table.

Normal forms: 1NF requires atomic values, 2NF requires 1NF plus no partial dependency, 3NF requires 2NF plus no transitive dependency.

SQL sub-languages: DDL (CREATE, ALTER, DROP), DML (SELECT, INSERT, UPDATE, DELETE), DCL (GRANT, REVOKE), TCL (COMMIT, ROLLBACK).

ACID properties of a transaction: Atomicity, Consistency, Isolation and Durability.

ER diagram symbols: rectangle = entity, ellipse = attribute, diamond = relationship, line = association between them.

JOIN types: INNER (matching rows only), LEFT/RIGHT OUTER (all rows of one table), FULL OUTER, CROSS (Cartesian product).

Integrity rules: entity integrity requires a primary key to be unique and not null; referential integrity requires a foreign key to match an existing primary key or be null.

WHERE filters individual rows before grouping; HAVING filters groups after GROUP BY.

SDLC phases: planning, analysis, design, implementation, testing, deployment and maintenance.

Methodologies: waterfall (sequential), prototyping, RAD, spiral (risk-driven) and agile (iterative and incremental).

Fact-finding techniques: interviews, questionnaires, observation, document review, JAD sessions and sampling.

Feasibility types: technical, economic, operational, legal and schedule.

DFD symbols: process (circle or rounded rectangle), data store (open-ended rectangle), external entity (rectangle) and data flow (labelled arrow).

The context diagram is the level-0 DFD: one process representing the whole system, surrounded by external entities.

Conversion strategies: direct (cheapest, riskiest), parallel (safest, costliest), phased and pilot.

System types: TPS, MIS, DSS, EIS and KWS (knowledge work systems).

Economic evaluation measures: payback period, return on investment, net present value and cost-benefit ratio.

CIA triad: confidentiality, integrity and availability.

Authentication factors: something you know (password), something you have (token), something you are (biometrics); MFA combines two or more factors.

Malware types: virus (needs a host file), worm (self-replicating across networks), trojan (disguised as legitimate), ransomware (encrypts data for payment), spyware.

Symmetric encryption uses one shared key (AES, DES); asymmetric encryption uses a public/private key pair (RSA); hashing is one-way (SHA-256, MD5).

Control categories: preventive, detective, corrective and deterrent; implemented as administrative, technical (logical) or physical controls.

Access control models: MAC, DAC and RBAC; least privilege and need-to-know reduce exposure.

Backups: full, incremental (changes since the last backup of any type) and differential (changes since the last full backup); RAID 0 = striping, RAID 1 = mirroring, RAID 5 = striping with parity.

Network defences: firewall (packet filtering), IDS/IPS, VPN (encrypted tunnel), DMZ for public-facing servers and regular patching.

BCP keeps the business operating while DRP restores IT services; RTO is maximum tolerable downtime and RPO is maximum tolerable data loss.

HTML provides structure (tags), CSS provides presentation and JavaScript provides behaviour.

Basic HTML document structure: , , (title, meta tags) and (visible content).

CSS placement: inline (style attribute), internal (

Static pages return identical content to every user; dynamic pages are generated per request by server-side scripts such as PHP, ASP.NET or JSP.

HTTP is stateless; GET appends data to the URL and is size-limited, POST sends data in the request body.

URL structure: protocol://host:port/path?query#fragment.

Bitmap formats: JPEG (photographs, lossy), PNG (lossless, supports transparency), GIF (256 colours, animation); vector format: SVG.

Multimedia elements: text, graphics, audio, video and animation; common formats MP3/WAV for audio and MP4/AVI for video.

Multimedia quality factors: resolution (pixels), colour depth (bits per pixel), frame rate (fps) and compression type (lossy or lossless).

Project triple constraint: scope, time and cost, with quality at the centre; changing one constraint affects the others.

Project phases: initiation, planning, execution, monitoring and control, and closure.

A work breakdown structure decomposes project deliverables into manageable work packages.

A Gantt chart shows task durations against a calendar; CPM/PERT networks show dependencies and identify the critical path, which has zero float.

Risk management steps: identify, assess (probability x impact), plan response (avoid, mitigate, transfer, accept) and monitor.

Software licence types: proprietary/commercial, open source, freeware, shareware and public domain.

Professional ethics principles: integrity, objectivity, confidentiality, competence and professional behaviour.

Data protection principles: collect lawfully for a specified purpose, keep accurate and current, retain no longer than necessary, keep secure and honour subject access rights.

Business ownership forms: sole proprietorship, partnership, private limited company and public limited company; a business plan covers market, operations, management and financials.