Basic Network Terminology

What is the term "Network"?

A network is a system where two or more computers and devices are connected to each other to share common resources.

Resources can include:

• Data: Files and folders

• Hardware: Devices such as printers

• Services: For example, internet sharing

LAN (Local Area Network)

A Local Area Network (LAN) is a network that connects computers and other devices within a limited geographic area—such as a home, school, office building, or campus. It enables users to share resources like files, printers, and internet access with high speed and low latency.

Reference (Practical): LANs are typically owned, controlled, and managed by a single organization or individual. — Cisco Networking Basics

WAN (Wide Area Network)

A Wide Area Network (WAN) is a telecommunications network that extends over a large geographic area and connects multiple smaller networks, such as LANs or metro area networks (MANs). WANs are used by businesses, governments, and other organizations to connect branch offices, data centers, and remote users.

Reference (Practical): WANs often rely on third-party carriers or internet service providers (ISPs) and use technologies such as MPLS, VPNs, or leased lines. — CompTIA Network+ Certification Guide

Small, Medium, and Enterprise Network Classification

Network Topology

Point-to-point:

• Point-to-point link: direct connection between two nodes.

• Guarantees consistent bandwidth since only two devices share it.

• Can be physical (single cable) or logical (via intermediate networks).

• Example: two routers on a WAN can have a logical point-to-point link despite multiple underlying connections.

• Key feature: 1-to-1 relationship between the devices.

Star Topology

• Star topology: each endpoint connects to a central device (e.g., switch or router).

• The central node manages communication between all endpoints.

• Most commonly used physical topology, especially in LANs and SOHO networks.

• Example: SOHO networks use a central router with wired or wireless client connections.

• Advantages:

  • Easy to reconfigure and troubleshoot

  • Central point allows network monitoring and management

  • Fault isolation is straightforward (node, media, or central device)

• Hub-and-spoke topology:

  • Same physical layout as star

  • Used mainly in WANs to connect remote sites, not LANs

Mesh Topology

• Mesh topology is common in WANs, including public networks like the Internet.

• A full mesh requires every device to have a point-to-point link with every other device.

• Full mesh is usually impractical due to the high number of links needed:

  • Formula: n(n–1)/2, where n = number of nodes

  • Example:

    • 4 nodes → 6 links

    • 40 nodes → 780 links

• Instead, a partial mesh is often used:

  • Only key devices are fully interconnected

  • Additional links may be added for redundancy and fault tolerance

• Partial mesh balances performance, cost, and complexity.