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====== MAC addresses ======

MAC address is a unique identifier assigned to [[nic|NIC]]. It is used for IEEE 802 networking technologies: [[wi-fi|Wi-Fi]], [[ethernet|Ethernet]], and [[bluetooth|Bluetooth]]. Within [[osi_model|OSI]] it's used at the [[network-layer_datalink|Data Link layer]].

MAC addresses can technically be changed, just like [[ip-address|IP addresses]]. For example, with ifconfig on Linux.

While IP addresses work end to end, MAC addresses work hop to hop.

MAC structure:
{{ :mac-48_address.svg |}}

Each MAC address consists of 48 bits or 6 octets.

In the first octet the last 2 bits are significant: one determines if the address is universal vs local. Universal address is assigned by the manufacturer, while the local one is set by the network administrator. The other bit determines if it's unicast vs multicast.

Special addresses: \\
FF:FF:FF:FF:FF:FF - broadcasting \\
33:33:00:00:00:00 - limited broadcasting