How long is a MAC address?

A MAC address is 48 bits (6 bytes) long.

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#Short version for an interview

The length of a MAC address is 48 bits, that is 6 bytes.

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#In detail, in plain language

#What this looks like in practice

48 bits are usually written:

• in hexadecimal format
• 2 characters per byte

Example:

AA:BB:CC:DD:EE:FF

Every two characters = 1 byte In total:

• 6 pairs → 6 bytes → 48 bits

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#What these 48 bits consist of

A MAC address is logically split into two parts:

1. The first 24 bits (3 bytes) - the OUI the manufacturer identifier
2. The last 24 bits (3 bytes) - a unique device number

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#An important nuance (for extra credit at an interview)

There are also:

• 64-bit MAC addresses (EUI-64)

They are used:

• in some technologies
• for example, when forming IPv6 addresses

But the classic MAC in Ethernet is always 48 bits.

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#Quick comparison

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#Summary

A standard MAC address is 48 bits (6 bytes) long and is used at the data link layer to address devices on a local network.