Know and understand internet protocols including HyperText Transfer Protocol (HTTP), HyperText Transfer Protocol secure variant (HTTPS), File Transfer Protocol (FTP), Secure Socket Layer (SSL)

ICT 0417 – Complete Syllabus Notes (Cambridge IGCSE / A‑Level)

1. Hardware, Input/Output, Storage & Networks

• CPU (Central Processing Unit) – executes instructions; consists of Control Unit, ALU and registers.
• Memory

  • RAM (Random‑Access Memory) – volatile, fast, holds data while the computer is on.
  • ROM (Read‑Only Memory) – non‑volatile, stores firmware such as BIOS.
  • Cache – very small, high‑speed memory close to the CPU.

• Operating‑system types

  • CLI (Command‑Line Interface) – e.g., MS‑DOS, Linux terminal.
  • GUI (Graphical User Interface) – Windows, macOS, Android, iOS.
  • Mobile OS – Android, iOS; optimised for touch, power‑efficiency.
  • Key functions: resource management, file system, security, user interface.

• Input devices – keyboard, mouse, scanner, microphone, touch screen, digital camera. Consider ergonomics and data‑entry accuracy.
• Output devices – monitor, printer, speakers, projector. Distinguish raster (bitmap) and vector displays.
• Storage media

  • Magnetic: HDD, floppy, tape.
  • Solid‑state: SSD, USB flash drive, memory card.
  • Optical: CD‑ROM, DVD, Blu‑ray.
  • Cloud storage – remote servers accessed via the Internet; advantages (access anywhere, automatic backup) and disadvantages (dependence on connectivity, security).

• Network fundamentals

  • Topologies – star, bus, ring, mesh; star is easy to isolate faults, bus suffers from collisions.
  • Key devices

    • Router – forwards data between networks, assigns IP addresses (DHCP).
    • Switch – connects devices within a LAN, uses MAC addresses.
    • Modem – converts digital signals to analog for telephone or cable lines.
    • Access point – provides Wi‑Fi connectivity.

  • IP addressing – IPv4 (32‑bit, dotted decimal) vs IPv6 (128‑bit, hexadecimal). Subnetting basics.
  • DNS (Domain Name System) – translates domain names to IP addresses.
  • Client‑server model – clients request services; servers provide resources (web pages, files, databases).

• Emerging technology impact (brief) – AI‑driven tutoring apps, AR/VR visualisations, and IoT sensors are extending the range of ICT applications in education and industry.

2. Effects of ICT & Applications

• Positive effects

  • Speed of communication, instant access to information.
  • Support for education (e‑learning, virtual labs) and business (e‑commerce, automation).
  • Facilitates collaboration across distances.

• Negative effects

  • Health issues – eye strain, headaches, repetitive‑strain injury (RSI); prevention: regular breaks, ergonomic setup.
  • E‑waste – discarded devices contain hazardous materials; recycling programmes reduce impact.
  • Digital divide – unequal access to hardware, broadband, and digital skills.
  • Privacy & security concerns – data mining, identity theft, cyber‑bullying.
  • Environmental impact – energy consumption of data centres.

• ICT applications (selected syllabus sub‑topics)

  Application area	Typical example
  School‑management system	Attendance and grades stored in a relational database.
  Booking system	Online room reservation for a university.
  Banking/ATM	Secure transaction processing using encryption.
  Medical information system	Electronic patient records with access control.
  Expert system	Diagnostic tool for plant diseases.
  Retail POS / EFTPOS	Barcode scanner linked to inventory database.
  Recognition systems	OCR for digitising printed forms; RFID for stock tracking; biometric fingerprint login.
  Satellite / GPS	Navigation app showing real‑time location.
  Simulation / Modelling	Spreadsheet model of a small business cash flow.

3. Systems Life‑Cycle, Safety & Security, Audience & Copyright

• Systems Life‑Cycle (SLC)

  1. Analysis – identify user needs, define requirements.
  2. Design – plan hardware, software architecture, data structures, UI mock‑ups.
  3. Development – write or adapt code, create databases, configure hardware.
  4. Testing – unit, integration and acceptance testing; fix defects.
  5. Implementation – install system, migrate data, train users.
  6. Evaluation – review against objectives, collect feedback, plan maintenance and future upgrades.

• Safety & e‑safety checklist

  • Physical safety – tidy workspace, ergonomic chairs/desks, avoid overheating equipment.
  • Data protection – strong passwords, two‑factor authentication, regular backups (3‑2‑1 rule).
  • Malware protection – up‑to‑date anti‑virus, firewalls, safe browsing habits.
  • Legal & ethical – respect privacy, comply with data‑protection regulations (GDPR, Data Protection Act).

• Audience awareness – adapt language, layout and level of detail for primary, secondary or specialist users.
• Copyright & licensing

  • Copyright protects original literary, artistic, musical and software works.
  • Fair dealing / fair use – limited copying for teaching, research, review.
  • Creative Commons licences – CC‑BY, CC‑BY‑SA, CC‑BY‑NC, etc.

4. Communication & File Management

• Electronic communication tools – email, instant messaging, video conferencing, blogs, discussion forums, social media.
• Email etiquette – clear subject, professional greeting, concise body, appropriate signature, correct use of CC/BCC.
• File‑management concepts

  • File types – text, binary, executable, image, audio, video.
  • File extensions – .docx, .pdf, .jpg, .mp3, .zip.
  • Folder hierarchy – logical structure (e.g., Project > Phase > Documents).
  • Compression – ZIP, RAR; lossless vs. lossy.
  • Backup strategies – 3‑2‑1 rule (3 copies, 2 media types, 1 off‑site).

5. Images, Layout, Styles & Proofing

• Image formats

  • Raster – BMP, GIF, JPEG, PNG, TIFF (pixel‑based, resolution matters).
  • Vector – SVG, EPS, AI (mathematically defined, scalable).

• Basic image editing – cropping, resizing, colour correction, layers, transparency.
• Document layout principles – alignment, proximity, contrast, repetition, white space.
• Styles – paragraph, character, table, list; use of style sheets for consistency.
• Proof‑reading techniques – spell‑check, grammar check, peer review, read aloud, verify formatting.

6. Document Production (Word Processing)

• Creating and formatting text – fonts, sizes, colour, bold/italic/underline.
• Paragraph formatting – alignment, indentation, line spacing, justification.
• Tables – inserting, merging cells, applying table styles.
• Headers, footers, page numbers, footnotes/endnotes.
• Using templates and master documents.
• Inserting graphics, hyperlinks, bookmarks.
• Mail merge – generating personalised letters or labels.

7. Databases

• Relational database concepts

  • Table – rows (records) and columns (fields).
  • Primary key – unique identifier for each record.
  • Foreign key – links to a primary key in another table.
  • Normalization – reducing redundancy (1NF, 2NF, 3NF).

• Database objects

  • Forms – data‑entry screens.
  • Queries – SELECT statements, criteria, sorting, calculated fields.
  • Reports – formatted output, grouping, totals.

• Common operations – add, edit, delete records; import/export CSV, XML.
• Security – user accounts, passwords, read/write permissions, role‑based access.

8. Presentations

• Slide master – consistent layout, background, logo.
• Use of multimedia – inserting images, audio, video, animations.
• Effective design – limited text per slide, high‑contrast colours, readable fonts (≥24 pt for headings).
• Transitions and animation – purposeful, not distracting.
• Speaker notes and handouts.
• Delivery tips – pacing, eye contact, rehearsal.

9. Spreadsheets

• Cell referencing – relative, absolute (\$A\$1) and mixed references.
• Formulas and functions – SUM, AVERAGE, IF, VLOOKUP/HLOOKUP, COUNTIF, DATE, TEXT.
• Data analysis – sorting, filtering, pivot tables, conditional formatting.
• Charts – column, line, pie, scatter; choosing the appropriate chart type.
• What‑if analysis – Goal Seek, Scenario Manager.
• Protection – locking cells, worksheet and workbook passwords.

10. Website Authoring & Internet Protocols

10.1. Basic Web Technologies

• HTML (HyperText Markup Language) – defines structure of web pages (elements, attributes, nesting).
• CSS (Cascading Style Sheets) – controls presentation (selectors, properties, layout models).
• Responsive design – media queries, flexible grids, viewport meta tag.

10.2. HyperText Transfer Protocol (HTTP)

• Purpose – transfer hypertext documents and associated resources between client (browser) and server.
• Default port – 80.
• Stateless nature – each request is independent; sessions are maintained with cookies or server‑side mechanisms.
• Common request methods

  • GET – retrieve data (no request body).
  • POST – send data to server (e.g., form submission).
  • PUT – upload/replace a resource.
  • DELETE – remove a resource.
  • HEAD – like GET but without a response body.

• Status‑code families

  Code	Meaning	Example
  1xx	Informational	100 Continue
  2xx	Success	200 OK, 201 Created
  3xx	Redirection	301 Moved Permanently, 302 Found
  4xx	Client error	404 Not Found, 403 Forbidden
  5xx	Server error	500 Internal Server Error

• Message structure

  1. Request line – method, URI, HTTP version.
  2. Headers – Host, User‑Agent, Accept, Cookie, etc.
  3. Optional body (for POST/PUT).
  4. Response line – HTTP version, status code, reason phrase.
  5. Response headers – Content‑Type, Content‑Length, Set‑Cookie, etc.
  6. Optional response body – HTML, JSON, image, etc.

10.3. HyperText Transfer Protocol Secure (HTTPS)

• Purpose – provide confidentiality, integrity and authentication for HTTP traffic.
• Default port – 443.
• TLS handshake (simplified)

  1. ClientHello – TLS version, supported cipher suites, random data.
  2. ServerHello – chosen version & cipher suite, server certificate.
  3. Client verifies certificate (trusted CA, validity, domain match).
  4. Key exchange (RSA, Diffie‑Hellman, ECDHE) creates a shared symmetric session key.
  5. Both sides send Finished messages encrypted with the session key.
  6. Subsequent HTTP messages are encrypted (AES, ChaCha20, etc.).

• Indicators of a secure site – https:// in the address bar, padlock icon, certificate details (issued to, issued by, validity period).
• TLS versions – TLS 1.2 and TLS 1.3 are recommended; TLS 1.0/1.1 are deprecated.

10.4. File Transfer Protocol (FTP)

• Purpose – transfer files between a client and a server.
• Default ports – 21 for control commands, 20 for data (active mode). Passive mode uses a random high port for data.
• Operation modes

  • Active mode – client opens control connection to port 21; server opens data connection from port 20 to a client‑specified port.
  • Passive mode – client opens both control and data connections to ports supplied by the server (works better with firewalls).

• Common FTP commands – USER, PASS, LIST, RETR (download), STOR (upload), DELE, RNFR/RNTO (rename), MKD, RMD.
• Security considerations

  • Credentials and data are sent in clear text – vulnerable to sniffing.
  • Secure alternatives:

    • FTPS – FTP over SSL/TLS (explicit on port 21 or implicit on port 990).
    • SFTP – SSH File Transfer Protocol (uses SSH, default port 22).

10.5. Secure Socket Layer (SSL) / Transport Layer Security (TLS)

• Purpose – provide encryption, authentication and data integrity for any application protocol (e.g., HTTPS, FTPS, SMTP‑TLS).
• Key components

  • Handshake – negotiates protocol version, cipher suite, and authenticates parties.
  • Cipher suite – combination of key‑exchange algorithm (RSA, DH, ECDHE), symmetric cipher (AES, 3DES, ChaCha20) and hash function (SHA‑256, SHA‑3).
  • Certificates – X.509 digital certificates issued by a Certificate Authority (CA) bind a public key to a domain.

• Typical workflow for a secured connection

  1. Client initiates TLS handshake.
  2. Server presents its X.509 certificate.
  3. Client validates the certificate chain.
  4. Both parties agree on a cipher suite and generate a shared symmetric key.
  5. All subsequent data is encrypted with that symmetric key.

• Current best practice – use TLS 1.3 where possible, disable older protocols and weak cipher suites, obtain certificates from trusted CAs, and renew them before expiry.