Know and understand the differences and similarities between an extranet, intranet and the internet

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ICT 0417 – Networks: Extranet, Intranet and Internet

4. Networks and the Effects of Using Them

Objective

Know and understand the differences and similarities between an extranet, intranet and the internet.

Key Definitions

  • Internet: The global public network that connects millions of private, public, academic, business, and government networks worldwide. It uses the TCP/IP protocol suite and is accessible to anyone with an appropriate connection.
  • Intranet: A private network that uses the same technologies as the internet (e.g., TCP/IP, HTTP) but is restricted to members of an organisation. It is typically used for internal communication, document sharing, and business applications.
  • Extranet: A controlled extension of an intranet that provides limited access to external users such as partners, suppliers, or customers. Access is granted through secure methods (VPN, firewalls, authentication).

Comparison of Features

Feature Internet Intranet Extranet
Scope of users Public – anyone worldwide Private – employees and authorised internal staff Restricted – internal staff plus selected external parties
Access control None (open) – security relies on individual sites Strong – firewalls, authentication, internal policies Strong – VPN, firewalls, user‑level permissions
Typical uses Web browsing, email, social media, cloud services Internal portals, HR systems, file servers, internal email Supplier portals, customer support sites, joint project spaces
Network infrastructure Public service providers, backbone routers, DNS Organisation’s LAN/WAN, internal routers, private DNS Organisation’s LAN/WAN plus secure gateway to external users
Security concerns High – exposure to malware, phishing, DDoS Medium – internal threats, insider misuse Medium‑high – need to protect internal data while allowing external access
Cost of implementation Low for end‑user (subscription); high for providers Moderate – hardware, software, maintenance Higher – additional security devices, VPN licences, monitoring

Similarities

  • All three use the same fundamental protocols (TCP/IP, HTTP/HTTPS, DNS).
  • Data is transmitted in packets across routers and switches.
  • Security measures such as encryption (SSL/TLS) can be applied to any of them.
  • They can all host web‑based applications and services.

Differences – Summary

  1. Accessibility: Internet is open to anyone; intranet is closed to the organisation; extranet is partially open to selected outsiders.
  2. Purpose: Internet provides global information exchange; intranet supports internal collaboration; extranet enables controlled collaboration with external partners.
  3. Security level: Internet relies on site‑level security; intranet and extranet require organisational security policies and devices.
  4. Management: Internet is managed by multiple ISPs; intranet and extranet are managed by the owning organisation.

Advantages and Disadvantages

Network Type Advantages Disadvantages
Internet
  • Universal access
  • Vast amount of information and services
  • Low cost for end users
  • High security risk
  • Uncontrolled content
  • Potential for bandwidth congestion
Intranet
  • Secure environment for sensitive data
  • Improved internal communication
  • Customised applications for the organisation
  • Limited to internal users
  • Requires maintenance and IT support
  • Potential for siloed information if not integrated
Extranet
  • Facilitates collaboration with partners
  • Reduces need for physical meetings
  • Can improve supply‑chain efficiency
  • Complex security management
  • Higher implementation cost
  • Risk of data leakage if permissions are mis‑configured

Key Points to Remember

  • All three networks rely on the same core technologies but differ in scope and security.
  • Intranets are completely internal; extranets are a bridge between internal and external users.
  • Effective use of an extranet requires robust authentication, encryption, and monitoring.
  • Choosing between them depends on the organisation’s need for openness versus control.
Suggested diagram: Venn diagram showing overlap of users and services among Internet, Intranet and Extranet, with arrows indicating data flow and security boundaries.