Network Hardware and Addresses

A network interface card (NIC) provides a device with an interface for network communication, wired or wireless. A MAC address identifies an interface on a local network; factory-assigned addresses are a useful basic model, although devices may use private/randomised addresses.

An IP address identifies a network connection for routing between networks. IPv4 uses 32-bit addresses, commonly written as four decimal groups. IPv6 uses 128-bit addresses, usually written in hexadecimal groups, supporting a much larger address space. An IP address may change when a device connects elsewhere; do not confuse it with a URL or a person's identity.

A router forwards packets between networks, using the destination IP address and routing information. A home router connects the local network to the internet. Many home routers also provide address allocation and wireless access, but those are distinct functions.

Worked journey

A laptop requests a page from a server on another network. Its NIC transmits on the local network; the router forwards packets towards the server's IP address. DNS supplied the address from the host name. The MAC is useful for local delivery; routers use IP information for the journey between networks.

Independent application

A laptop changes from home Wi-Fi to school Wi-Fi. Explain why its network configuration can change while the same web URL still works. Identify where NIC, router and DNS each help.