Figure 4-7 shows
the relationships of bit signi?¬?cance to the values for base 10 and base 2 numbering systems.
Figure 4-7 Bit Signi?¬?cance
15 1111
16 10000
17 10001
18 10010
19 10011
Table 4-1 Decimal Versus Binary Numbers (Continued)
Decimal Number Binary Number
Base-10 Decimal Conversion - 63204829
107
6
10000000
60000000
106
3
1000000
3000000
105
2
100000
200000
104
0
10000
0
103
4
1000
4000
102
8
100
800
101
2
10
20
100
9
1
9
MSB LSB
Decimal Weight
Column Value
BaseExponent
Column Weight
60000000 + 3000000 + 200000 + 0 + 4000 + 800 + 20 + 9 = 63204829
Base-2 Binary Conversion - 1110100 (233)
27
1
128
128
26
1
64
64
25
1
32
32
24
0
16
0
23
1
8
8
22
0
4
0
21
0
2
0
20
1
1
1
MSB LSB
Decimal Weight
Column Value
BaseExponent
Column Weight
128 + 64 + 32 + 0 + 8 + 0 + 0 + 1 = 233
Understanding Binary Numbering 249
Base 2 Conversion System
Understanding the base 2 system is important because an IP version 4 (IPv4) address
consists of 32 binary bits. Each digit is 1 bit. The 32 bits are divided into four sets of 8 bits,
called octets. A dot (period) is placed between each set to separate them. (A byte is another
name for 8 bits; however, for the purposes of this module, 8 bits will be referred to as an
octet.
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