Binary Numbers and Their Hex Equivalents

Although there's a lot more to hex, you don't really have to understand how hex numbering works to appreciate why it is used for Ethernet addresses. Instead of writing down Ethernet addresses as 48-digit binary numbers, you can write them as 12-digit hex numbers because each hex digit represents 4 binary digits. For instance, if the first 4 binary digits of an Ethernet address were 0010, then the first hex digit would be a 2. If the next 4 binary digits were 1010, the next hex digit would be A, and so on.

When you see a hex number, just know that each hex digit represents four binary digits. For example, when you're using gear from Cisco Systems, the device will list Ethernet addresses in the following format:

15CD.3412.5BDA

0200.2222.2222