Key Terms
- IP address: Logical address assigned to a device for routing across networks — can change
- MAC address: Physical hardware address permanently burned into a NIC at manufacture
- IPv4: 32-bit IP address format (e.g. 192.168.1.1) — approximately 4.3 billion addresses
- IPv6: 128-bit IP address format (e.g. 2001:0db8::1) — vastly more addresses
- NIC: Network Interface Card — the hardware component that connects a device to a network
- DHCP: Protocol that automatically assigns IP addresses to devices on a network
Must-Know Facts
- IP address is logical — can be changed or reassigned (dynamic via DHCP)
- MAC address is physical — permanently burned into NIC at factory, cannot change
- IPv4 = 32 bits; IPv6 = 128 bits
- MAC address = 48 bits, written in hexadecimal (e.g. AA:BB:CC:DD:EE:FF)
- IP used for routing across networks (Internet); MAC used for delivery within a LAN
- IPv6 was developed because IPv4 addresses were running out
- Routers use IP addresses; switches use MAC addresses
Key Concepts
- Why both are needed: IP routes packets across the Internet; MAC delivers them to the correct device on the local network
- IP address analogy: Like a postal address — identifies location, can change if you move
- MAC address analogy: Like a fingerprint — unique identity, stays with the device always
- Why IPv6 was needed: Only ~4.3 billion IPv4 addresses — not enough for every internet-connected device
Common Mistakes
- Saying MAC addresses can change: MAC addresses are permanently burned into the network interface card (NIC) by the manufacturer — they are fixed hardware addresses, unlike IP addresses which can be reassigned
- Confusing the roles of IP and MAC addresses: IP addresses are used for routing packets between networks (Internet level); MAC addresses are used to deliver data to the correct device within a local network
- Saying routers use MAC addresses: Routers use IP addresses to route packets between networks; switches use MAC addresses to forward frames within a LAN
- Not knowing why IPv6 was introduced: IPv4 uses 32 bits (~4.3 billion addresses) which ran out due to the growth of internet-connected devices; IPv6 uses 128 bits, providing vastly more addresses
This topic summary covers Knowledge Organiser: IP and MAC Addresses within IP & MAC Addresses for GCSE Computer Science. Revise IP & MAC Addresses in 3.5 Fundamentals of Computer Networks for GCSE Computer Science with 15 exam-style questions and 18 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 9 of 9 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for IP & MAC Addresses
Which of the following correctly describes an IP address?
Explain three differences between an IP address and a MAC address.