Know and understand characteristics, uses and purpose of an extranet, intranet and the internet

Topic: Networks and the Effects of Using Them

Objective (AO1)

Know and understand the characteristics, uses and purpose of an extranet, intranet and the Internet, and be able to relate them to the wider Cambridge IGCSE 0417 syllabus (including AO2 design and AO3 analysis).

Key Definitions

• Internet – A global public network that interconnects millions of private, public, academic, business and government networks.
• Intranet – A private network that uses Internet protocols (TCP/IP) and web technologies but is restricted to an organisation’s internal users.
• Extranet – A controlled extension of an intranet that gives selected external users (partners, suppliers, customers) limited access.

Network Hardware & Wireless Technologies (Why it matters – AO3)

• Router – Directs data between different networks (e.g., between a LAN and the Internet). Why it matters: without routing, devices on separate networks could not communicate.
• Network Interface Card (NIC) – Provides a device with a physical (wired) or wireless connection to a network. Why it matters: the NIC is the point at which data enters/exits a computer.
• Hub – Repeats incoming signals to all ports; creates a single collision domain. Why it matters: leads to bandwidth inefficiency and is therefore rarely used in modern networks.
• Switch – Connects multiple devices on a LAN and forwards frames only to the intended recipient, creating separate collision domains. Why it matters: improves speed and security; “smart” switches can also perform VLAN tagging and QoS.
• Bridge – Connects two separate LAN segments and filters traffic, reducing collisions. Why it matters: useful for segmenting large networks without a full‑size router.
• Wi‑Fi (Wireless LAN) – Uses IEEE 802.11 radio waves to provide wireless connectivity within a limited area. Why it matters: enables mobility but introduces security considerations (encryption, SSID hiding).
• Bluetooth – Short‑range (PAN) wireless technology (typically 2.4 GHz) for peripherals, IoT devices and file transfer. Why it matters: convenient for keyboards, headsets, wearables; security relies on pairing, PINs and BLE encryption.
• Cloud computing – Delivery of storage, applications and services over the Internet (SaaS, PaaS, IaaS). Why it matters: the cloud is dependent on reliable network connectivity and raises issues of data security, bandwidth usage and vendor lock‑in.

Network Types & Environments (AO1)

• LAN (Local Area Network) – Covers a single building or campus (e.g., a school computer lab).
• WLAN (Wireless LAN) – LAN that uses Wi‑Fi; typical in cafés, libraries and offices.
• WAN (Wide Area Network) – Connects geographically dispersed sites (e.g., a multinational corporation’s offices).
• MAN (Metropolitan Area Network) – Spans a city or large campus; example: city‑wide public Wi‑Fi or a university’s fibre backbone.
• PAN (Personal Area Network) – Very short range, usually Bluetooth between personal devices (smartphone ↔ smartwatch).
• Client‑Server – Centralised model where servers provide resources to client computers (e.g., a school’s file server).
• Peer‑to‑Peer (P2P) – Decentralised model where each computer can act as both client and server; common use case: file‑sharing applications such as BitTorrent.

Characteristics of Internet, Intranet and Extranet

• Ownership

  • Internet – No single owner; collectively owned by many organisations, governments and private entities.
  • Intranet – Owned and managed by a single organisation.
  • Extranet – Owned by a single organisation but access is granted to selected external parties.

• Access control

  • Internet – Open to anyone with an ISP connection.
  • Intranet – Restricted to authorised internal users (employees, management).
  • Extranet – Restricted to authorised internal users and specific external users (partners, suppliers, customers).

• Security level

  • Internet – Varies widely; security depends on user practices and protective measures (firewalls, VPNs, encryption, anti‑malware).
  • Intranet – Higher; protected by internal firewalls, strong authentication, and organisational policies.
  • Extranet – Highest; combines intranet security with additional controls for external users (VPN tunnels, two‑factor authentication, access‑control lists).

• Typical technologies – TCP/IP, HTTP/HTTPS, DNS, VPN, firewalls, SSL/TLS, LDAP/Active Directory for authentication.

Real‑World Case Study (AO2)

School intranet: A secondary school runs an intranet portal where teachers upload lesson plans, students submit assignments and the administration accesses HR and payroll systems. Access is limited to staff and students via a username/password login.

Supplier extranet: The same school uses an extranet to let textbook suppliers upload stock lists and receive purchase orders. Suppliers connect through a VPN and must use two‑factor authentication before accessing the order‑processing application.

Uses and Purposes (AO1)

• Internet

  • Research and information retrieval.
  • Communication – email, social media, video‑conferencing.
  • E‑commerce and online services.
  • Cloud computing and SaaS.

• Intranet

  • Internal communication – portals, internal email.
  • Document management and shared repositories.
  • Internal applications – HR, payroll, inventory.
  • Collaboration tools for project teams.

• Extranet

  • Supplier and partner collaboration – order processing, inventory sharing.
  • Customer self‑service portals – account information, support tickets.
  • Secure data exchange with external consultants or contractors.
  • Joint development environments for multiple organisations.

Security & Communication Issues (AO3)

• Password & authentication checklist

  1. Use at least 12 characters, mixing upper‑ and lower‑case letters, numbers and symbols.
  2. Avoid dictionary words, personal information and repeated characters.
  3. Change passwords every 60–90 days.
  4. Store passwords securely (e.g., password manager).
  5. Enable two‑factor authentication (required for extranet access).

• Anti‑malware protection – Install reputable antivirus/anti‑spyware, keep definitions up‑to‑date and scan all downloads and email attachments.
• Data‑transfer risks – Data can be intercepted (Man‑in‑the‑Middle). Mitigate by using HTTPS, VPN encryption and verifying digital certificates.
• Electronic conferencing – Video (Zoom, Teams), audio (Skype), web‑conferencing (Webex). Requires sufficient bandwidth, good quality microphones/webcams and security settings such as meeting passwords and waiting rooms.
• Privacy – Follow data‑protection policies (GDPR/POPIA). Limit personal data shared on public networks and configure privacy settings on social platforms.

Impact of Networks on Health & Society (AO3)

• Physical health – Prolonged screen time on LAN/WLAN devices can cause eye strain, headaches and musculoskeletal problems. Encourage the 20‑20‑20 rule and ergonomic workstations.
• Psychological effects – Constant connectivity via the Internet or extranet can increase stress and reduce face‑to‑face interaction.
• Digital divide – Limited access to high‑speed WAN or broadband Internet widens socioeconomic gaps, especially in rural areas.
• Data‑privacy concerns – The more data stored on intranets/extranets, the greater the risk of unauthorised access; organisations must implement strong authentication and regular audits.

Comparison Table (AO1)

Advantages and Disadvantages (AO3)

1. Internet

   • Advantages – Global reach, vast information resources, many services.
   • Disadvantages – Variable security, risk of cyber‑attacks, information overload.

2. Intranet

   • Advantages – Secure environment, tailored to organisational needs, improves internal communication.
   • Disadvantages – Requires ongoing maintenance, limited to internal users, may become a “silo” if not integrated with external systems.

3. Extranet

   • Advantages – Facilitates collaboration with external partners, improves supply‑chain efficiency, controlled access.
   • Disadvantages – More complex security management, higher setup cost, need for strict access policies and monitoring.

Practical Task (AO2)

Design a simple network diagram that shows the relationship between the Internet, an organisation’s Intranet and an Extranet.

• Use a free online diagram tool (e.g., draw.io, Lucidchart, Google Slides).
• Include at least one router, one switch, a Wi‑Fi access point and a server for the intranet.
• Show an external partner computer connected to the extranet via a VPN tunnel.
• Label each device and indicate the type of network (LAN, WAN, etc.).
• Demonstrate at least one “layer” of the three‑layer web model (presentation, data, physical) to satisfy the AO2 requirement for later web‑development topics.
• Submit the diagram as a PNG or PDF and write a short paragraph (≈100 words) explaining how security is maintained at each level (Internet, Intranet, Extranet).

Summary (AO1)

The Internet, intranet and extranet share common networking technologies but differ in scope, ownership, access control, security level and typical users. Understanding these distinctions, together with the relevant hardware, network types, security considerations and societal impacts, equips learners to evaluate which network solution best fits public communication, internal collaboration or secure interaction with external stakeholders.