Default masks for various networks

The default mask of A-type network is 255.0.0.0, which is converted into a binary value of 11111111.20.0000.00000000.00000000. The default mask means that A-type large network (A-type Network) is not divided into several small networks. 1 In the mask indicates the network number, and 24 0 indicates that when the network number is determined (the left eight digits of the IP address represented in binary are fixed ), the 24-bit binary number is used to represent the host number of the IP address. (The IP address consists of the network number and host number)

The default mask of the B-type network is 255.0.0, which is converted into a binary value of 11111111.111111.20.2.16.00000000. The default mask means that the B-type network is not divided into several small networks. 16 zeros indicate that when the network number is determined (the left 16 digits of the IP address in binary format remain unchanged), the 16-digit binary number can be used to represent the host number of the IP address. (It can be understood that the default mask of Class B is to divide a type-a large network (Class-A network) into eight power (256) Small networks) of 2)

The default mask of the class C network is 255.255.255.0, And the binary mask is 11111111.111111.111111.00000000. The default mask means that the class C network is not divided into several small networks. Here, the 8 zeros indicate that, when the network number is determined (the 24-bit left side of the IP address in binary format remains unchanged), the 8-bit binary number can be used to represent the host part of the IP address. (The default Class C mask can be understood as dividing a type-a large network (Class-A network) into a 16-power (or 65536) small network of 2, is to divide B type big network into 2 eight power (that is, 256) Small Network)