Know and understand Local Area Network (LAN), Wireless Local Area Network (WLAN), Wide Area Network (WAN) and the differences between these networks

4. Networks and the Effects of Using Them

Learning Objective (AO1)

Know and understand the main network types – LAN, WLAN, WAN, PAN, MAN, Intranet, Extranet and the Internet – and the key networking devices, media, security and communication issues associated with them.

1. Key Networking Devices (AO1)

Compare / Contrast: When to Choose Which Device (AO2)

• Hub vs. Switch – Hubs broadcast to all ports, causing collisions and limiting speed; switches isolate traffic, support full‑duplex, and are the default for any modern LAN.
• Bridge vs. Switch – Both operate at Layer 2, but a bridge connects only two segments and has limited ports; a switch replaces a hub and can interconnect many devices with higher performance.
• Router vs. Switch – Switches work within a single IP subnet; routers are required to move traffic between different subnets or to the Internet.

2. Network Types & Typical Environments (AO1)

3. Definitions of the Three Core Network Types (AO1)

• Local Area Network (LAN) – A network covering a small geographical area such as a single building or campus, normally using Ethernet cabling or fibre.
• Wireless LAN (WLAN) – A LAN that uses radio waves (Wi‑Fi) instead of copper/fibre; conforms to the IEEE 802.11 family of standards.
• Wide Area Network (WAN) – A network that spans a large geographical area, linking multiple LANs/WLANs via leased lines, satellite, MPLS or the public Internet.

4. Characteristics of LAN, WLAN and WAN (AO1)

5. Advantages & Disadvantages (AO2)

Local Area Network (LAN)

• Advantages

  • Very high data‑transfer speeds (up to 10 Gbps).
  • Low latency – ideal for real‑time applications such as online gaming or video conferencing.
  • Physical security is easier to enforce (locked rooms, cable control).
  • Predictable performance – no interference from external radio sources.

• Disadvantages

  • Requires cabling – installation cost and disruption during upgrades.
  • Physical damage to cables or switches can cause total loss of connectivity.
  • Less flexible for temporary or mobile workstations.

Wireless LAN (WLAN)

• Advantages

  • Mobility – users can connect anywhere within the radio coverage.
  • Quick deployment, especially in historic or rented buildings where cabling is impractical.
  • Supports BYOD (Bring Your Own Device) policies.
  • Scalable – additional access points (APs) can be added without rewiring.

• Disadvantages

  • Potential interference from microwaves, Bluetooth devices, neighbouring Wi‑Fi networks.
  • Signal attenuation through walls, floors and metal objects.
  • Security must be robust (WPA3, strong passphrases, regular key rotation) because radio signals travel through the air.
  • Higher latency and lower maximum throughput compared with a wired LAN.

Wide Area Network (WAN)

• Advantages

  • Connects geographically dispersed sites, enabling real‑time collaboration.
  • Provides access to cloud services and the public Internet.
  • Scalable – new sites can be added by provisioning additional leased lines or VPN tunnels.
  • Redundancy can be built in (dual‑homed links, SD‑WAN).

• Disadvantages

  • Higher latency and often lower speeds than LAN/WLAN.
  • Reliance on external providers increases cost and reduces direct control.
  • Security is more complex (VPNs, firewalls at multiple points, IDS/IPS).
  • Troubleshooting can be harder because faults may lie with the provider.

6. Wi‑Fi and Bluetooth (AO1)

• Wi‑Fi (WLAN) – Implements IEEE 802.11a/b/g/n/ac/ax/ay standards. Typical indoor range 30 m, outdoor up to 100 m. Security protocols: WPA2‑Personal/Enterprise, WPA3‑Personal/Enterprise; optional 802.1X authentication for large organisations.
• Bluetooth – Short‑range radio (up to 100 m for Bluetooth 5). Used for peripherals (keyboards, mice, headphones) and IoT sensors. Security: pairing with passkey or numeric comparison, AES‑CCM encryption, and optional Secure Simple Pairing (SSP).

7. Cloud Computing (AO1)

Definition: Delivery of computing resources (servers, storage, applications) over a network, typically the Internet.

• Service models

  • IaaS – Infrastructure as a Service (e.g., Amazon EC2, Microsoft Azure VMs).
  • PaaS – Platform as a Service (e.g., Google App Engine, Heroku).
  • SaaS – Software as a Service (e.g., Google Workspace, Microsoft 365).

• Link to networking – Cloud services are accessed via WAN links; secure access is achieved with TLS/SSL, VPN tunnels or Zero‑Trust Network Access (ZTNA).
• Advantages – On‑demand scalability, reduced on‑site hardware, pay‑as‑you‑go pricing.
• Disadvantages – Dependence on Internet connectivity, data‑privacy concerns, ongoing subscription costs.

8. Network Security & Communication (AO2)

Security Measures (with practical examples)

• Passwords & Authentication

  • Complex, unique passwords (minimum 12 characters, mixed case, numbers, symbols).
  • Multi‑factor authentication (MFA) for admin accounts – e.g., authenticator app + password.

• Anti‑malware & Updates

  • Endpoint protection (Windows Defender, Bitdefender) with real‑time scanning.
  • Patch management – schedule monthly Windows Update and firmware updates for switches/routers.

• Firewalls & VPNs

  • Perimeter firewall rule‑set example: Allow TCP 80/443 to DMZ web server; Deny all else.
  • IPsec site‑to‑site VPN linking the school LAN to a partner university’s network.

• Encryption

  • WPA3‑Personal on all school WLANs.
  • TLS 1.3 for web traffic (HTTPS) and SMTP‑STARTTLS for email.
  • End‑to‑end encryption for messaging apps (Signal, WhatsApp).

• Physical Security

  • Locked server rooms, CCTV, badge‑controlled access.
  • Cable locks on desktop PCs and network switches.

Electronic Conferencing – Quick Checklist (AO2)

9. Effects of Using Networks (AO3)

10. Typical Real‑World Examples (AO1)

• School computer lab – Wired LAN (switch → PCs & server) for file/print sharing and local web services.
• Café free Wi‑Fi – WLAN with a guest SSID, WPA3‑Personal, bandwidth‑shaped to protect the back‑office network.
• Multinational corporation – WAN linking offices in London, New York and Tokyo via leased fibre and MPLS; corporate intranet for staff, extranet for approved suppliers.
• Smart home – PAN using Bluetooth for speakers and sensors, connected to a home router (WLAN) for Internet access.
• School intranet – Internal web portal accessible only from the school LAN/WLAN, hosting timetables, staff notices and a secure file‑share for teachers.

11. Suggested Diagram