MAC addresses are expressed in hexadecimal (base‑16). Digits 0‑9 and letters A‑F represent values 0‑15.
Decimal
Hex
Binary
0
0
0000
1
1
0001
2
2
0010
3
3
0011
4
4
0100
5
5
0101
6
6
0110
7
7
0111
8
8
1000
9
9
1001
10
A
1010
11
B
1011
12
C
1100
13
D
1101
14
E
1110
15
F
1111
Excel/LibreOffice Conversion Formulas
=DEC2HEX(255) → returns FF
=HEX2DEC("FF") → returns 255
What is a MAC Address?
A Media Access Control (MAC) address is a 48‑bit hardware identifier burned into a network interface card (NIC). It is written as 12 hexadecimal digits, often grouped in pairs (e.g., 00:1A:2B:3C:4D:5E).
First 24 bits: Organizationally Unique Identifier (OUI) assigned by IEEE to the manufacturer (e.g., Cisco, Intel).
Last 24 bits: Network Interface Controller (NIC)‑specific identifier, assigned by the manufacturer.
Unicast: The first octet's least significant bit (LSB) is 0. Used for one‑to‑one communication.
Broadcast:FF:FF:FF:FF:FF:FF – sent to all devices on the local network.
Multicast: First octet LSB is 1; used for one‑to‑many groups.
Properties of MAC Addresses
Burned‑in: Permanently stored in the NIC’s ROM. Cannot be physically changed.
Software change possible: Operating systems allow “spoofing” (temporary override). If you reinstall the OS, the original MAC returns.
Security implications: MAC filtering (whitelist/blacklist) on Wi‑Fi routers can restrict access, but because MACs can be spoofed, it is not a strong security measure. An attacker can impersonate a trusted device by cloning its MAC.
Used for: Switch learning, ARP resolution, and local network communication.