MAC Addresses (Media Access Control)
Part of IP & MAC Addresses — GCSE Computer Science
This key facts covers MAC Addresses (Media Access Control) within IP & MAC Addresses for GCSE Computer Science. Revise IP & MAC Addresses in Networks for GCSE Computer Science with 15 exam-style questions and 18 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 3 of 8 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 3 of 8
Practice
15 questions
Recall
18 flashcards
MAC Addresses (Media Access Control)
What is a MAC Address?
A physical hardware address permanently burned into every Network Interface Card (NIC) at the factory. Uniquely identifies the physical device.
- Purpose: Uniquely identify physical network hardware
- Permanent: Cannot be changed (burned into NIC at manufacture)
- 48 bits: 6 bytes (octets)
- Operates at: Link layer (Layer 1 of TCP/IP)
- Analogy: Like a fingerprint or serial number - identifies WHO device is
MAC Address Format:
- 48 bits written as 12 hexadecimal digits
- Format: AA:BB:CC:DD:EE:FF or AA-BB-CC-DD-EE-FF
- Example: 00:1A:2B:3C:4D:5E
- First 3 bytes (24 bits): Manufacturer ID (OUI - Organizationally Unique Identifier)
- Last 3 bytes (24 bits): Device serial number (assigned by manufacturer)
MAC Address Examples:
00:1A:2B:3C:4D:5E - Apple device
00:50:56:XX:XX:XX - VMware virtual NIC
08:00:27:XX:XX:XX - VirtualBox virtual NIC
(First 3 bytes identify manufacturer)
Where MAC Addresses are Used:
- Local delivery: Switches use MAC to deliver frames to correct device on LAN
- ARP (Address Resolution Protocol): Maps IP addresses to MAC addresses
- Network filtering: Routers can allow/block specific MAC addresses
- Device tracking: MAC address can identify specific hardware