This topic covers the basics of networking, including the definition of a network, types of networks (LAN, WAN, MAN), and the importance of networking in today's digital world.
Introduction to Networking – Study Notes
| Concept | Description |
|---|---|
| Definition | A collection of interconnected devices (computers, servers, phones, IoT gadgets, etc.) that can share resources and data. |
| Purpose | Enable communication, resource sharing (files, printers, internet), and collaboration across distances. |
| Key Benefits | • Faster information exchange • Centralized data management • Cost‑effective resource utilization • Improved reliability and scalability |
| Term | Meaning |
|---|---|
| Node | Any device (host, router, switch, printer) attached to a network. |
| Host | A node that runs applications and provides services (e.g., a PC or server). |
| Link | Physical or logical connection between two nodes (cable, fiber, wireless). |
| Protocol | A set of rules that define how data is formatted, transmitted, and received (e.g., TCP, HTTP). |
| Topology | Physical or logical layout of the network (star, mesh, bus, ring, tree). |
| LAN | Local Area Network – confined to a single building or campus (typically ≤ 1 km). |
| WAN | Wide Area Network – spans cities, countries, or the globe (e.g., the Internet). |
| IP Address | Numerical identifier for a device on an IP network (IPv4: 192.168.1.10; IPv6: 2001:db8::1). |
| MAC Address | Hardware address burned into a NIC; unique per network interface (e.g., 00:1A:2B:3C:4D:5E). |
| Port | Logical endpoint for a specific service on a host (e.g., TCP 80 = HTTP). |
| Layer (OSI Model) | Primary Function | Common Protocols / Devices |
|---|---|---|
| 1 – Physical | Transmit raw bits over a medium (copper, fiber, radio). | Ethernet cables, fiber optics, Wi‑Fi radios. |
| 2 – Data Link | Frame creation, MAC addressing, error detection. | Ethernet (802.3), Wi‑Fi (802.11), Switches, Bridges. |
| 3 – Network | Routing, logical addressing, path selection. | IP, ICMP, Routers, Layer‑3 switches. |
| 4 – Transport | End‑to‑end reliability, flow control, multiplexing. | TCP, UDP. |
| 5 – Session | Manage dialogs, synchronization. | NetBIOS, RPC. |
| 6 – Presentation | Data translation, encryption, compression. | SSL/TLS, JPEG, ASCII ↔ Unicode. |
| 7 – Application | User‑level services and interfaces. | HTTP, FTP, DNS, SMTP, SSH. |
The TCP/IP model condenses these into four layers (Link, Internet, Transport, Application) and is the practical basis for most modern networks.
| Device | Role | Typical Use Cases |
|---|---|---|
| Hub | Repeats incoming signals to all ports (Layer 1). | Small, legacy labs (rare today). |
| Switch | Forwards frames based on MAC address (Layer 2). | Core of LANs, VLAN segmentation. |
| Router | Routes packets between different IP subnets ( |