Network Cell number Host number

Network Cell number host number

The first example: known ip:192.169.20.50 subnet mask: 255.255.255.224 to seek network cell number host number.

First, the subnet mask 255.255.255.224 is converted to bits

255.255.255.224:11111111.11111111.11111111.11100000

You can see that the left side of this mask is the same as the Class C default mask, only the fourth section is different from the Class C default mask, that is, the subnet mask grows in the fourth section, so you can think of this 255.255.255.224 mask is within the Class C default mask range, which means that the class C network is subnetting. We look at 224:11.1 million, because 1 represents the network number, so 11100000 means that the class C network is divided into (111) 2 3 8-party subnets, so that the class C is divided into 8 subnets, the number of IP addresses per subnet is:

256 (fixed number)/8 (subnet number) =32 (subnet block size), then these eight subnet numbers are: (that is, starting from 0 each hop plus 30. )

192.169.20.0
192.169.20.32
192.169.20.64
192.169.20.96
192.169.20.128
192.169.20.160
192.169.20.192
192.169.20.224

The algorithm of broadcast address is except 192.169.20.0, other sub-net number minus 1, and 192.169.20.255
It is:
192.169.20.31
192.169.20.63
192.169.20.95
192.169.20.127
192.169.20.159
192.169.20.191
192.169.20.223

The host number is all addresses except the network number and broadcast address.
192.169.20.1~30
192.169.20.33 ~ 63
192.169.20.65 ~ 95
192.169.20.97 ~ 127
192.169.20.129 ~ 159
192.169.20.161 ~ 191
192.169.20.193 ~ 223
192.169.20.225 ~ 254
Get their

Network number is 192.169.20.32
Address range is 192.169.20.33~94

Let's look at the following example: (A fast algorithm)

Known computer IP address 192.169.20.25, subnet mask is: 255.255.255.240, calculated to write out the machine's network number, subnet number, host number.

First 256-240=16 (the calculation of the subnet block size), that is, the block size 16 is the number of subnet segments.

256 (fixed number)/16 (subnet fast size) =16 (number of subnets), then these 16 subnet numbers are:

192.169.20.0               192.169.20.16 
192.169.20.32              192.169.20.48 
192.169.20.64              192.169.20.80 
192.169.20.96              192.169.20.112 
192.169.20.128             192.169.20.144 
192.169.20.160             192.169.20.176 
192.169.20.192             192.169.20.208 
192.169.20.224             192.169.20.240 

The host number is all except network number and broadcast address (except network number 192.169.20.0, other network number minus 1 plus 192.169.20.255 total 16) all addresses:

192.169.20.1~14 192.169.20.17~30
192.169.20.33 ~ 46 192.169.20.49~62
192.169.20.65 ~ 78 192.169.20.81~94
192.169.20.97 ~ 110 192.169.20.113~126
192.169.20.129 ~ 142 192.169.20.145~158
192.169.20.161 ~ 174 192.169.20.177~190
192.169.20.193 ~ 206 192.169.20.209~222
192.169.20.225 ~ 238 192.169.20.241~254

The active host is 14.

25 between 17-30 then the subnet address is 192.169.20.16 Broadcast address is 192.169.20.31

The address range is: 192.169.20.17-192.169.20.30

The following is for the first example (the first example: known ip:192.169.20.50 subnet mask: 255.255.255.224 to find the network cell number host number. ) to make some further summaries:

Knowing that the subnet mask value is 224 so the network is divided into 8 subnets, there are two ways to calculate 8,

One is: 224:11.1 million, because 1 represents the network number, so 11100000 means that the class C network is divided into (111) 2 3 8-party subnets, so that the class C is divided into 8 subnets network.

The second is: 256-224=32 (the calculation of the subnet block size), that is, the block size 32 is the number of subnet segments. 256 (fixed number)/32 (subnet fast size) =8 (number of subnets)