WACE Applied IT cheat sheet

Project life cycle phases: initiation, planning, execution, monitoring and control, closure; each phase produces a deliverable that feeds the next.

Work breakdown structure (WBS) decomposes deliverables into work packages; a work package is the smallest unit that can be estimated and assigned.

Critical path is the longest dependent sequence through a network diagram; its duration equals the minimum project duration, and any delay on it delays the project.

Float (slack) = late start − early start; activities with zero float lie on the critical path.

Gantt charts show duration and sequence on a time axis but do not show dependencies as clearly as network diagrams.

Design process stages: problem definition, research, ideation, prototyping, testing/evaluation, refinement; iteration returns to any earlier stage.

Scope creep is uncontrolled expansion of project scope without matching adjustment to time, cost, or resources.

A milestone has zero duration and marks a checkpoint; it consumes no resources and is not a task.

Triple constraint: scope, time, and cost are interdependent; changing one requires adjusting at least one other, with quality as the balancing outcome.

Von Neumann architecture: CPU (control unit, ALU, registers), memory, input/output, and buses; instructions and data share the same memory.

CPU performance is influenced by clock speed (Hz), cores, cache size, and instruction pipelining; clock speed alone is not a reliable comparison between different architectures.

RAM is volatile and holds currently executing programs; ROM is non-volatile and typically holds firmware such as the boot loader.

Storage hierarchy by speed and cost per gigabyte: registers, cache, RAM, SSD, magnetic HDD, optical, tape.

SSDs use flash memory with no moving parts, giving faster random access and greater shock resistance than HDDs; HDDs are cheaper per gigabyte at high capacity.

System software (operating system, utilities, drivers) manages hardware; application software performs user tasks.

Utility software categories include antivirus, backup, disk defragmentation, compression, and file managers.

Open-source software distributes source code with a licence permitting modification and redistribution; proprietary software restricts these rights.

File compression may be lossless (reversible, e.g. PNG, ZIP) or lossy (discards data permanently, e.g. JPEG, MP3).

Relational database components: tables (relations), records (rows/tuples), fields (columns/attributes), primary key (unique identifier), foreign key (references another table's primary key).

Normalisation reduces redundancy: 1NF removes repeating groups, 2NF removes partial dependencies on part of a composite key, 3NF removes transitive dependencies on non-key fields.

SQL clauses execute logically in the order FROM, WHERE, GROUP BY, HAVING, SELECT, ORDER BY; WHERE filters rows before grouping, HAVING filters groups after.

Validation checks data on entry (type, range, list, presence, format); verification confirms accuracy by double entry or visual comparison.

Backup types: full (all data), incremental (changes since last backup of any type), differential (changes since last full backup).

Encryption converts plaintext to ciphertext using a key; symmetric uses one shared key, asymmetric uses a public/private key pair.

Malware categories: virus (attaches to files), worm (self-replicating across networks), trojan (disguised as legitimate), ransomware (encrypts data for extortion), spyware (covertly collects data).

Access control principle of least privilege grants only the permissions needed for a task; authentication factors are knowledge, possession, and inherence.

Data integrity risks include accidental corruption, unauthorised modification, and transmission errors; checksums and hashes detect change but do not prevent it.

Network topologies: star (central switch, single point of failure at the hub), bus (shared backbone, collisions), ring (token passing), mesh (redundant paths, high cost).

LAN covers a limited area under one administrative control; WAN spans large distances; the internet is a global network of networks.

OSI layers top to bottom: Application, Presentation, Session, Transport, Network, Data Link, Physical.

TCP is connection-oriented and guarantees ordered delivery with retransmission; UDP is connectionless with lower overhead, used for streaming and voice.

IP addresses identify hosts; DNS resolves domain names to IP addresses; DHCP automatically assigns IP configuration; NAT translates private to public addresses.

IPv4 uses 32-bit addresses; IPv6 uses 128-bit addresses, providing a vastly larger address space.

Bandwidth is maximum theoretical transfer capacity; throughput is actual achieved rate, reduced by latency, congestion, and protocol overhead.

Wi-Fi security standards in order of strength: WEP (broken), WPA, WPA2, WPA3; WPA2/WPA3 use AES encryption.

Netiquette and online communication conventions: clear subject lines, quoted context in replies, avoidance of all-caps, awareness of audience and permanence of posts.

Spreadsheet relative references (A1) adjust when copied; absolute references ($A$1) do not; mixed references lock one component.

Common spreadsheet functions: SUM, AVERAGE, COUNT, COUNTA, IF(condition, true, false), VLOOKUP(value, range, column_index, FALSE), and COUNTIF for conditional counting.

Chart selection rule: column/bar for comparison, line for trend over time, pie for parts of a whole (few categories), scatter for correlation.

Word processing features: styles for consistent formatting, mail merge combining a main document with a data source, tables of contents generated from heading styles.

Database queries and reports: queries extract and filter records; reports present formatted output for a defined audience.

Presentation design: one idea per slide, minimum font sizes for legibility, consistent templates, alt text on images for accessibility.

File formats: native editable formats versus portable formats (PDF) that preserve layout; CSV stores tabular text without formatting or formulas.

Data types must match field content (text, number, currency, date, boolean); mismatched types cause sorting and calculation errors.

Accessibility features: alternative text, captions, sufficient contrast, keyboard navigation, and heading structure for screen readers.

Digital divide refers to unequal access to technology and skills, driven by income, geography, age, and education.

Employment effects: automation displaces routine tasks while creating roles in maintenance, data, and design; reskilling determines individual outcomes.

Ergonomic risk factors in computer use include sustained posture, repetitive movement, and screen glare; preventive measures include adjustable seating, breaks, and monitor positioning.

Privacy risks arise from data collection, cookies, tracking, and data breaches; privacy principles include consent, purpose limitation, and minimal collection.

Intellectual property categories: copyright (automatic on creation), patents (registered, novel inventions), trademarks (brand identifiers), trade secrets.

Cyberbullying and online harassment are amplified by anonymity and permanence of digital content; reporting and blocking tools are platform-level responses.

E-waste contains toxic materials (lead, mercury, cadmium); responsible disposal includes certified recycling and manufacturer take-back schemes.

Digital footprint is the persistent record of online activity; it is visible to employers and institutions and is difficult to erase fully.

Reliance on technology creates vulnerability to outages, cyberattack, and loss of manual skills; redundancy and backups mitigate this.

Artificial intelligence systems learn patterns from data; machine learning requires representative training data, and biased data produces biased outputs.

Large language models generate text probabilistically and can produce plausible but incorrect output (hallucination); outputs require verification.

Cloud computing service models: IaaS (infrastructure), PaaS (platform), SaaS (software); deployment models include public, private, and hybrid.

Internet of Things connects embedded sensors and devices to networks; risks include insecure default credentials and large attack surfaces.

Blockchain is a distributed, append-only ledger secured by cryptographic hashing and consensus; immutability makes correction of errors difficult.

5G offers higher bandwidth and lower latency than 4G, enabling real-time applications but requiring dense infrastructure.

Edge computing processes data near its source, reducing latency and bandwidth use compared with sending all data to centralised cloud servers.

Quantum computing uses qubits and superposition; it threatens current public-key encryption, motivating post-quantum cryptography.

Automation and robotics raise questions of accountability when autonomous systems cause harm; responsibility typically rests with designers, operators, or regulators.