what is MAC-48 address?

Answer 1

In computer networking a Media Access Control address (MAC address) is a unique identifier attached to most network adaptors (NICs). It is a number that acts like a name for a particular network adaptor, so, for example, the network cards (or built-in network adaptors) in two different computers will have different names, or MAC addresses, as would an Ethernet adaptor and a wireless adaptor in the same computer, and as would multiple network cards in a router.
Most layer 2 network protocols use one of three numbering spaces managed by the IEEE: MAC-48, EUI-48, and EUI-64,
The original IEEE 802 MAC address, now officially called "MAC-48", comes from the Ethernet specification.