Hexadecimal conversion is the same as decimal and binary conversion, but you are working with a larger base numbering system. Hexadecimal is a Base 16 numbering system, which means that each place can hold 16 values. These values are 0 through F.

Nope, that is not a typo. Since there are no single numbers in the decimal system larger than 9, we have to use the first 6 letters of the alphabet, A through F, to get our 16 values.

Convert Decimal to Hex

In the CCNA exam you may need to demonstrate your ability to convert 8-bit binary numbers to hexidecimal. This is important to know because MAC addresses are 48-bit numbers used to identify Network Interface Cards (or "NICs" tech lingo). These naddresses are broken down into six byte-sized pieces. Literally, byte-sized meaning 8-bits long. But wait, there's more! Each 8-bit piece is separated into two 4-bit sections called words, so you get 2 hex values. Here is an example of a MAC address: 00:1C:5F:23:3A:FF. Here is the same MAC address in binary:

00000000.00011100.01011111.00100011.00111010.11111111

Look at the chart to see how the 16 hex values translate to decimal. You can see that 0 - 9 are the same in decimal but A = 10, B = 11, C = 12, D = 13, E = 14, and F = 15

Hex  0   1   2   3   4   5   6   7   8   9   A    B   C   D   E    F

Dec  0   1   2   3   4   5   6   7   8   9   10  11  12  13  14  15

Convert Binary to Hex

Using the chart above, it will be easier to convert binary to decimal and decimal to hex. Take the binary number 11010011 and convert it to decimal (remember that you need to split the 8-bit number into two 4-bit parts: word1 and word2. This makes it easier to work with as you will see below):

           word1                    word2

  8      4       2       1      8      4      2      1 (remember from binary conversion each place is 2^n)

  1      1       0       1      0      0      1      1

Where there is a one, add the number above for each 4-bit section:

8 + 4 + 1 = 13    and 2 + 1 = 3

Convert the numbers to Hex using the reference chart and you get:  D3

For the CCNA exam, you only need to go this far. Remember to understand that MAC addresses are six 8-bit numbers, but each 8-bit number is represented by two 4-bit hex values. Hexadecimal numbers are base 16, which means that each place can hold one of sixteen values. The values are represented as 0 - F.