MAC Addresses

MAC Addresses is a uniqe identifier and 48 bit address 

example :- B3:2B:6F:D7:C3:A3

is total possibilities is 281,474,976,710,656

 the first three ictets of a MAC address is (OUI - organizationally unique identifier) 

A Unicast transmission is always meant for just one receiving address

A multicast is send and receive data

A boardcast is send data to everyone

IPv4:-