Baidu Encyclopedia
Subnet mask (subnet mask) is also called network mask, address mask, and subnet mask. It is a type used to indicate which bits of an IP address identify the subnet where the host is located, and which bits identify the host's bit mask. The subnet mask cannot exist alone, it must be used in conjunction with the IP address. The subnet mask has only one function, which is to divide a certain IP address intoNetwork addressandHost addressTwo parts
24-bit subnet mask (255.255.255.0)
What we often see now is192.168.0.0/24, that is, the subnet mask is255.255.255.0, the computer that can be stored is256 - 1 - 1 - 1 = 253,in0 is the network address，255It's the broadcast address,1It is the gateway address.
23-bit subnet mask (255.255.254.0)
192.168.6.0/23For this network, the number of computers we can store512 - 1 - 1 - 1 = 509
First we convert IP into binary192.168.6.0—> 1100 0000. 1010 1000. 0000 0110. 0000 0000
Subnet mask23Before explaining the IP address23bit network address, so1100 0000. 1010 1000. 0000 011is the network address,0. 0000 0000As the host address
That is, the host has 9-bit binary, so corresponding to binary, that is,192.168.6.0and192.168.7.0It is in the same network segment.
25-bit subnet mask (255.255.255.128)
192.168.6.0/25For this network, the number of computers we can store128 - 1 - 1 - 1 = 125
First we convert IP into binary192.168.6.0—> 1100 0000. 1010 1000. 0000 0110. 0000 0000
Subnet mask25Before explaining the IP address25bit network address, so1100 0000. 1010 1000. 0000 0110. 0is the network address,000 0000As the host address
That is, the host has a 7-digit binary number.192.168.6.0arrive192.168.6.127The corresponding network segments are between them.
Store 10 computers
Filed10lie in8to16between, the corresponding host address is at least 4 bits, that is192.168.6.0/28
The corresponding network IP number is192.168.6.1arrive192.168.6.14
Store 100 units of calculation
Filed100lie in64to128between, the corresponding host address is at least 7 bits, that is192.168.6.0/25
The corresponding network IP number is192.168.6.1arrive192.168.6.126
Store 1,000 computers
Filed1000We'll have the first reaction1024，210Then the corresponding host address is at least 10 bits, that is,192.168.6.0/22
The corresponding network IP number is192.168.4.1arrive192.168.7.254
Store 5,000 computers
Mentioned5000A computer, then the corresponding one is4096arrive8192between. Then what we will use192.168.6.0/19。
The corresponding network IP number is192.168.0.1arrive192.168.31.254
Store 10,000 computers
The corresponding number is8192arrive16384,Right now192.168.6.0/18
The corresponding network IP number is192.168.0.1arrive192.168.63.254