Third, subnet division and instance
According to the above analysis, it is recommended to define subnet masks as follows and instances.
1. The number of subnets to be divided into 2 M times. To divide 8 subnets, 8 = 23.
2. Take the Power of the M-Party Power of 2 of the number of 2 points to be divided. Such as 23, m = 3.
3. The power m determined by the previous step is converted to a decimal system after the host address m bits. Such as m is 3
Then 11100000, converted to decimal 224, which is the final identified subnet mask. If it is Class C
Online, the subnet mask is 255.255.255.224; if it is a B network, the subnet mask is
255.255.224.0; if it is a C-network, the subnet mask is 255.224.0.0.
Here, the number of subnets and occupied host address bits are established: 2M = n. Among them, M
Indicates the number of bits of the host address; n represents the number of subnets divided.
According to these principles, a Class C network is divided into 4 subnets.
If we use the network number 192.9.200, the host IP address in the C-Class C network is
192.9.200.1 ~ 192.9.200.254 (because "0" and "1" host address have special
The meaning of the meaning, not as a valid IP address), is now divided into 4 parts, follow the steps:
4 = 22, the power of 22, that is, 2, the binary is 11, the high order of the host address is 11000000,
Convert to decimal 192. This makes it possible to determine that the subnet mask is: 192.9.200.192, 4
The IP address range of the subnet is:
Binary
Decimal
1 11000000 00001001 11001000 00000001
~
11000000 00001001 11001000 00111110
192.9.200.1
~
192.9.200.62
2 11000000 00001001 11001000 01000001
~
11000000 00001001 11001000 01111110
192.9.200.65
~
192.9.200.126
3 11000000 00001001 11001000 10000001
~
11000000 00001001 11001000 10111110
192.9.200.129
~
192.9.200.190
4 11000000 00001001 11001000 11000001
~
11000000 00001001 11001000 11111110
192.9.200.193
~
192.9.200.254
The number of A, B, and Class C class network subnets and a conversion table of the subnet mask is listed for reference.
Class A:
Number of subnets
Occupancy
Subnet mask
Number of hosts in the subnet
2
1
255.128.0.0
8,388,606
4
2
255.192.0.0
4,194,302
8
3
255.224.0.0
2,097,150
16
4
255.240.0.0
1,048,574
32
5
255.248.0.0
524,286
64
6
255.252.0.0
262, 142
128
Seduce
255.254.0.0
131,070
128
Seduce
255.255.0.0
65,534
Class B:
Number of subnets
Occupancy
Subnet mask
Number of hosts in the subnet
2
1
255.255.128.0
32,766
4
2
255.255.192.0
16,382
8
3
255.255.224.0
8,190
16
4
255.255.240.0
4,094
32
5
255.255.248.0
2,046
64
6
255.255.252.0
1,022
128
Seduce
255.255.254.0
510
256
8
255.255.255.0
254
Class C:
Number of subnets
Occupancy
Subnet mask
Number of hosts in the subnet
2
1
255.255.255.128
126
4
2
255.255.255.192
62
8
3
255.255.255.224
30
16
4
255.255.255.240
14
32
5
255.255.255.248
6
64
6
255.255.255.252
2
