🌐 Wide Area Network (WAN)

1. Definition

A WAN is a computer network that spans a large geographic area — from cities to entire countries or globally. It connects multiple LANs (Local Area Networks) together, enabling communication and resource sharing across long distances. 👉 The Internet itself is the largest WAN.

2. Key Characteristics

• Geographic scope: Covers wide regions, even worldwide.
• Infrastructure: Uses leased telecom lines, fiber optics, satellites, or VPNs.
• Ownership: Often a mix of private (corporate WANs) and public (Internet).
• Speed: Slower than LAN due to distance, but modern WANs can reach high bandwidth.
• Security: Needs encryption, firewalls, and VPNs to protect data.

3. Examples

• The Internet: Global WAN connecting billions of devices.
• Corporate WANs: Banks, airlines, and multinational companies linking branch offices.
• Government WANs: Defense or research networks (e.g., ARPANET was an early WAN).

4. Challenges

• Cost: Infrastructure like leased lines and satellites is expensive.
• Latency: Longer distances can mean slower response times.
• Security risks: More vulnerable to cyberattacks compared to LAN.

5. WAN vs Internet

• WAN ≠ Internet:
  • A WAN is the general concept of a wide‑area network.
  • The Internet is a public WAN, open to everyone.
• Private WANs also exist:
  • Corporations, banks, and governments often build their own WANs to securely connect branch offices worldwide.
  • These private WANs may or may not connect to the public Internet.

6. WAN vs LAN vs WLAN