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This lesson covers the key hardware components used in computer networks, as required by OCR J277 Section 1.3.1. You need to understand the purpose of switches, routers, wireless access points (WAPs), and network interface cards (NICs).
A NIC (Network Interface Card) is a hardware component that allows a device to connect to a network. Every device that connects to a network must have a NIC.
| Feature | Detail |
|---|---|
| Purpose | Enables a device to send and receive data over a network |
| Location | Built into the motherboard of most modern devices, or added as an expansion card |
| Types | Wired NIC (Ethernet port) and wireless NIC (WiFi adapter) |
| MAC address | Each NIC has a unique MAC (Media Access Control) address — a permanent identifier assigned during manufacture |
A MAC address is a 48-bit address written in hexadecimal, for example: A4:B1:C2:D3:E4:F5
A switch is a networking device that connects multiple devices within a LAN and directs data to the specific device it is intended for.
| Feature | Detail |
|---|---|
| Purpose | Connects devices in a LAN and forwards data to the correct recipient |
| How it works | Maintains a table of MAC addresses; when data arrives, it reads the destination MAC address and sends the data only to that port |
| Advantage over a hub | A switch sends data only to the intended device; a hub sends data to all connected devices (less efficient) |
| Location | Central device in a star topology |
| Feature | Switch | Hub |
|---|---|---|
| Data delivery | Sends to specific device only | Sends to all connected devices |
| Efficiency | High — reduces unnecessary traffic | Low — generates more traffic |
| Collisions | Rare | Common |
| Security | Better — data only goes to intended recipient | Poor — all devices see all data |
| Cost | More expensive | Cheaper |
| Modern use | Standard in most networks | Largely obsolete |
OCR Exam Tip: If asked about the difference between a switch and a hub, the key point is: a switch sends data only to the intended recipient using MAC addresses, while a hub broadcasts data to all devices.
A router is a networking device that directs data between different networks. Routers are essential for connecting a LAN to the internet (a WAN).
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