老谢博客

#
of Bits For Network ID

#
of Bits For Host ID

#
of Hosts Per Network

Prefix
Length in Slash Notation

Equivalent
Subnet Mask

#
of Equivalent “Classful” Addressing Networks

Class
A

Class
B

Class
C

1

31

2,147,483,646

/1

128.0.0.0

128

—

—

2

30

1,073,741,822

/2

192.0.0.0

64

—

—

3

29

536,870,910

/3

224.0.0.0

32

—

—

4

28

268,435,454

/4

240.0.0.0

16

—

—

5

27

134,217,726

/5

248.0.0.0

8

—

—

6

26

67,108,862

/6

252.0.0.0

4

—

—

7

25

33,554,430

/7

254.0.0.0

2

—

—

8

24

16,777,214

/8

255.0.0.0

1

256

—

9

23

8,388,606

/9

255.128.0.0

1/2

128

—

10

22

4,194,302

/10

255.192.0.0

1/4

64

—

11

21

2,097,150

/11

255.224.0.0

1/8

32

—

12

20

1,048,574

/12

255.240.0.0

1/16

16

—

13

19

524,286

/13

255.248.0.0

1/32

8

—

14

18

262,142

/14

255.252.0.0

1/64

4

—

15

17

131,070

/15

255.254.0.0

1/128

2

—

16

16

65,534

/16

255.255.0.0

1/256

1

256

17

15

32,766

/17

255.255.128.0

—

1/2

128

18

14

16,382

/18

255.255.192.0

—

1/4

64

19

13

8,190

/19

255.255.224.0

—

1/8

32

20

12

4,094

/20

255.255.240.0

—

1/16

16

21

11

2,046

/21

255.255.248.0

—

1/32

8

22

10

1,022

/22

255.255.252.0

—

1/64

4

23

9

510

/23

255.255.254.0

—

1/128

2

24

8

254

/24

255.255.255.0

—

1/256

1

25

7

126

/25

255.255.255.128

—

—

1/2

26

6

62

/26

255.255.255.192

—

—

1/4

27

5

30

/27

255.255.255.224

—

—

1/8

28

4

14

/28

255.255.255.240

—

—

1/16

29

3

6

/29

255.255.255.248

—

—

1/32

30

2

2

/30

255.255.255.252

—

—

1/64