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Networking Fundamentals · Foundational

MAC Address

A 48-bit Layer 2 address that identifies a network interface on a local network, written as 12 hexadecimal digits.

Definition

MAC addresses are formatted as six pairs separated by colons or hyphens (Linux, Windows) or three groups separated by dots (Cisco). The first 24 bits are the OUI identifying the manufacturer and the last 24 bits are assigned by the vendor. MAC addresses are used only within a broadcast domain; routers replace the source and destination MACs at each hop.

Example

Windows shows a MAC as 3C-52-82-1A-2B-3C, Cisco as 3c52.821a.2b3c.

Exam tip

MACs are 48 bits (6 bytes); IPv4 is 32 bits and IPv6 128 bits.

Don't confuse it with

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