Different hardware devices serve different purposes in a network.
Network Interface Card (NIC)
Definition
A NIC (Network Interface Card) connects a device to a network. Every NIC has a unique MAC address.
Switch
Definition
A switch connects devices within a LAN. It uses MAC addresses to forward data only to the intended recipient, making it more efficient than a hub.
Router
Definition
A router connects different networks together and routes data between them using IP addresses. Your home router connects your LAN to the internet (WAN).
Other Hardware
Key Point
| Device | Main function |
|---|---|
| WAP (Wireless Access Point) | Connects wireless clients to wired LAN |
| Gateway | Connects networks using different protocols |
| Bridge | Connects LAN segments at Layer 2 |
| Modem | Converts digital/analogue signals for transmission medium |
Key Point
MAC Address vs IP Address:
MAC Address:
• Physical/hardware address
• Unique to each NIC (burned in at manufacture)
• 48 bits, shown as hex (e.g., 00:1A:2B:3C:4D:5E)
• Works at Link layer
• Doesn't change (usually)
IP Address:
• Logical/software address
• Assigned by network (DHCP) or manually
• IPv4: 32 bits (e.g., 192.168.1.1)
• Works at Network layer
• Can change when you connect to different networks
MAC Address:
• Physical/hardware address
• Unique to each NIC (burned in at manufacture)
• 48 bits, shown as hex (e.g., 00:1A:2B:3C:4D:5E)
• Works at Link layer
• Doesn't change (usually)
IP Address:
• Logical/software address
• Assigned by network (DHCP) or manually
• IPv4: 32 bits (e.g., 192.168.1.1)
• Works at Network layer
• Can change when you connect to different networks
Hub and Repeater
Key Point
| Device | Main function |
|---|---|
| Hub | Receives data from one device and broadcasts it to every device connected to it. It does not read the address as a switch does, so it creates unnecessary traffic and is less secure |
| Repeater | Receives a signal and retransmits it at full strength, so that data can travel further along a cable or a wireless link |