CLEP Information Systems cheat sheet

Spreadsheet relative references (A1) shift when copied; absolute references ($A$1) stay fixed; mixed references lock only row ($A1) or column (A$1).

Common spreadsheet functions: SUM(range), AVERAGE(range), COUNT (numeric cells only), COUNTA (non-empty cells), IF(condition, true_value, false_value), VLOOKUP(lookup_value, table_array, col_index, FALSE for exact match).

A formula begins with =; a function is a built-in named operation; a cell reference points to a cell address; an operand is a constant or reference acted on by an operator.

Word-processing features: mail merge combines a main document with a data source; a macro records repeated keystrokes or commands; styles apply consistent formatting across headings and body text.

Presentation software: slide master controls global layout; transitions apply between slides; animations apply to objects within a slide; speaker notes are hidden from the audience.

Database office tools: a record is one row of related fields; a field is one column of one data type; a primary key uniquely identifies each record; a query retrieves records matching criteria.

File formats: .docx (Word document), .xlsx (Excel workbook), .pptx (PowerPoint presentation), .csv (comma-separated values, plain text), .pdf (fixed-layout portable document).

Productivity suites typically bundle word processing, spreadsheet, presentation, database, and email programs; cloud suites store files remotely and allow real-time co-authoring.

Keyboard shortcuts: Ctrl+C copy, Ctrl+X cut, Ctrl+V paste, Ctrl+Z undo, Ctrl+Y redo, Ctrl+S save, Ctrl+F find, Ctrl+P print; Ctrl+Home moves to the start of a document.

The Internet is a global network of networks using TCP/IP; the World Wide Web is a service on the Internet made of hyperlinked documents accessed by URL.

URL structure: scheme://host/path?query#fragment - scheme (http, https, ftp), host (domain name or IP), path (resource location), query (parameters), fragment (in-page anchor).

DNS translates human-readable domain names into IP addresses; a DNS resolver queries root, TLD, and authoritative name servers in sequence.

HTTP is a stateless request-response protocol; HTTPS adds TLS encryption; common methods are GET (retrieve), POST (submit data), PUT (replace), DELETE (remove).

Common status codes: 200 OK, 301 Moved Permanently, 304 Not Modified, 400 Bad Request, 401 Unauthorized, 403 Forbidden, 404 Not Found, 500 Internal Server Error.

HTML defines page structure (headings, paragraphs, links, images); CSS controls presentation (color, layout, fonts); JavaScript adds client-side interactivity.

A cookie is a small piece of data stored by the browser for a site; a session cookie expires when the browser closes; a persistent cookie has an expiration date.

Search operators: quotation marks for exact phrase, site: to restrict to a domain, minus sign to exclude a term, filetype: to restrict to a file extension.

Web 2.0 emphasizes user-generated content, social media, wikis, blogs, and AJAX-style asynchronous updates; Web 1.0 was largely static read-only pages.

CIA triad: confidentiality (only authorized readers), integrity (data not altered improperly), availability (systems accessible when needed).

Authentication verifies identity (something you know, have, or are); authorization determines what an authenticated user may do; accounting logs actions for audit.

Symmetric encryption uses one shared key (fast, e.g., AES); asymmetric encryption uses a public-private key pair (slower, e.g., RSA); TLS combines both in a handshake.

Hashing is a one-way function producing a fixed-length digest (e.g., SHA-256); it verifies integrity but is not encryption because it is not reversible.

Malware categories: virus (attaches to files), worm (self-replicates over networks), Trojan (disguised as legitimate), ransomware (encrypts and demands payment), spyware (secretly collects data).

Phishing is fraudulent email or messages that lure users to reveal credentials; spear phishing targets specific individuals; pharming redirects users to fake sites via DNS or hosts manipulation.

Firewalls filter traffic by rules; an intrusion detection system (IDS) monitors and alerts; an intrusion prevention system (IPS) can block detected attacks.

Access control models: discretionary (owner decides), mandatory (system labels and clearances), role-based (permissions by job role), least privilege (minimum rights needed).

Backup strategies: full (all data), incremental (changes since last backup), differential (changes since last full backup); a 3-2-1 rule keeps three copies, two media types, one off-site.

Von Neumann architecture: CPU (control unit + ALU), memory, input, output, and secondary storage connected by a bus; instructions and data share memory.

CPU performance factors: clock speed (GHz), cores, cache size, and instruction-level parallelism; more cores help parallel workloads, not single-threaded ones.

Memory hierarchy from fastest/smallest to slowest/largest: registers, L1/L2/L3 cache, RAM, SSD/HDD, tape or optical; cost per bit rises as speed rises.

RAM is volatile (loses contents on power loss); ROM is non-volatile; flash memory (SSD, USB) is non-volatile and faster than magnetic disks.

Storage units: 1 byte = 8 bits; 1 KB = 1024 bytes; 1 MB = 1024 KB; 1 GB = 1024 MB; 1 TB = 1024 GB.

Input devices: keyboard, mouse, scanner, microphone, touchscreen, camera; output devices: monitor, printer, speaker, projector; some devices are both (touchscreen).

Operating system functions: process management, memory management, file system management, device drivers, user interface, and security.

Cloud service models: IaaS (virtual machines, storage), PaaS (runtime and development platform), SaaS (finished application); deployment models include public, private, hybrid.

Virtualization runs multiple operating systems on one physical host via a hypervisor; containers share the host OS kernel and are lighter than virtual machines.

SDLC phases: planning, analysis, design, implementation (coding), testing, deployment, maintenance; iterative and agile models repeat these cycles.

Waterfall is sequential with fixed requirements; agile uses short iterations, continuous feedback, and adaptive planning; Scrum uses sprints, roles, and ceremonies.

Testing levels: unit (single component), integration (combined components), system (whole system), acceptance (user validation); regression testing checks that changes did not break existing features.

Black-box testing examines inputs and outputs without internal code knowledge; white-box testing examines internal paths and logic.

Programming paradigms: procedural (step-by-step functions), object-oriented (classes and objects), functional (pure functions), event-driven (responds to events).

Version control tracks changes; a repository stores history; commit saves a snapshot; branch isolates work; merge combines branches; conflict occurs when changes overlap.

Compiled languages translate source to machine code before execution (e.g., C, C++); interpreted languages execute line by line at runtime (e.g., Python, JavaScript).

Software quality attributes: correctness, reliability, usability, efficiency, maintainability, portability, and security.

Documentation types: user documentation (how to use), technical documentation (architecture and APIs), and inline code comments.

Data hierarchy: bit → byte/character → field → record → file → database; a database is an organized collection of related data managed by a DBMS.

Relational model: tables (relations) contain rows (tuples/records) and columns (attributes); a primary key uniquely identifies rows; a foreign key references a primary key in another table.

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

SQL clauses: SELECT columns FROM table WHERE condition GROUP BY column HAVING condition ORDER BY column; JOIN combines rows from related tables.

Normalization reduces redundancy: 1NF removes repeating groups; 2NF removes partial dependencies; 3NF removes transitive dependencies.

ACID properties: Atomicity (all or nothing), Consistency (valid state transitions), Isolation (concurrent transactions do not interfere), Durability (committed changes persist).

Programming constructs: sequence (ordered steps), selection (if/else, switch), iteration (for, while, do-while); variables store values; constants do not change.

Data types: integer, floating-point, character, string, Boolean, date; type determines allowed operations and storage size.

Algorithm properties: finite steps, definite instructions, input, output, effectiveness; pseudocode and flowcharts express algorithms independent of a language.

Digital divide refers to unequal access to computing devices, internet connectivity, and digital literacy across socioeconomic, geographic, or demographic groups.

Intellectual property protections: copyright (original expression), patent (inventions), trademark (brand identifiers), trade secret (confidential business information).

Software licensing models: proprietary (closed source, restricted use), open source (source available under a license such as GPL, MIT, Apache), freeware (free to use, source may be closed), shareware (trial then pay).

Net neutrality is the principle that ISPs treat all internet traffic equally without blocking, throttling, or paid prioritization.

Privacy principles: notice and consent, data minimization, purpose limitation, and the right to access or delete personal data (as in GDPR).

Computer crimes include unauthorized access, identity theft, fraud, cyberbullying, and distribution of malware; laws vary by jurisdiction.

Professional ethics codes (e.g., ACM, IEEE) emphasize honesty, avoiding harm, respecting privacy, and disclosing conflicts of interest.

Green computing aims to reduce energy use and e-waste through efficient hardware, virtualization, power management, and responsible recycling.

Accessibility standards (WCAG) require perceivable, operable, understandable, and robust content, including alternative text and keyboard navigation.