IP addresses and MAC addresses both identify endpoints in networking, but they answer different questions. A MAC address identifies built-in hardware on a LAN; an IP address identifies logical location on a network and is used when traffic is routed between networks.
Key points
Definition:MAC Address (separate idea): a unique identifier built into the device's network hardware (NIC), assigned by the manufacturer. Written in hexadecimal (e.g. 00:1A:2B:3C:4D:5E). Used for communication within a local network (LAN). It does not change — it is a permanent hardware address (burned into the NIC).
Definition:IP Address (separate idea): assigned to a device on a network to identify its logical location on that network. Can be static (fixed) or dynamic (can change over time or when reconnecting, e.g. via DHCP). Used for routing and for communication between networks — routers use the destination IP to decide the path.
MAC — 48 bits total: 6 groups of 2 hex digits, often shown with colons or hyphens. First part identifies the manufacturer (OUI); the rest is unique to the device.
IP — Logical address: must be unique on the network segment you are using at that moment, but the same device can get a different IP on a different network or after renewal if using DHCP.
IPv4 addresses are 32-bit: four decimal numbers separated by dots (e.g. 192.168.1.1).
IPv6 addresses are 128-bit: eight groups of four hexadecimal digits separated by colons.
Exam Tip:LAN delivery to a specific NIC is tied to MAC (switching). Getting traffic across the Internet between networks is tied to IP (routing).
Exam Tip:Key difference — IP addresses can CHANGE (especially dynamic IPs); MAC addresses are fixed at manufacture for the NIC.
Common Mistake:Saying MAC addresses can be changed by the user like an IP. For GCSE purposes they are built-in and do not change.
Common Mistake:Saying the router 'sends to the correct MAC' for everything on your Wi-Fi. The router routes using IP between networks; your combined home box also contains switching/Wi-Fi that delivers frames to MAC addresses on the LAN.
Exam Tip:IPv4 = 4 groups of 0-255 separated by DOTS. IPv6 = 8 groups of hex separated by COLONS. Common error: giving 6 groups for IPv6 or using dots instead of colons.