Information Technology Reference
In-Depth Information
Binary Numbers
The binary number system uses two digits: 1 and 0. Computer systems use binary num-
bers. IP addresses and MAC addresses are represented by binary numbers. The number of
binary 1s or 0s is the number of
bits
, short for binary digits. For example, 01101010 is a
binary number with 8 bits. An IP address has 32 bits, and a MAC address has 48 bits. As
shown in Table C-2, IPv4 addresses are usually represented in dotted-decimal format;
therefore, it is helpful to know how to convert between binary and decimal numbers.
MAC addresses are usually represented in hexadecimal numbers; therefore, it is helpful to
know how to convert between binary and hexadecimal.
The CCDA candidate should memorize Table C-3, which shows numbers from 0 to 16 in
decimal, binary, and hexadecimal formats.
Ta b l e C - 2
Binary Representation of IP and MAC Addresses
IPv4 Address in Binary
IPv4 Address in Dotted
Decimal
00101000 10001010 01010101 10101010
= 40.138.85.170
MAC Address in Binary
MAC Address in Hexadecimal
00001100 10100001 10010111 01010001 00000001
10010001
= 0C:A1:97:51:01:91
Ta b l e C - 3
Decimal, Binary, and Hexadecimal Numbers
Decimal Value
Hexadecimal
Binary
0
0
0000
1
1
0001
2
2
0010
3
3
0011
4
4
0100
5
5
0101
6
6
0110
7
7
0111
8
8
1000
9
9
1001
10
A
1010
11
B
1011
12
C
1100
