How to fill in the subnet mask

Subnet mask is an important concept used in the network to divide IP addresses and determine the network. Its correct filling is essential for the normal operation and communication of the network. So, next we will explain what a subnet mask is and how to fill it in.

First of all, the subnet mask is a 32-bit binary number that performs logical operations with the IP address to divide the network identification and the host identification. The function of the subnet mask is to divide the IP address into two parts: the network address and the host address. The number of 1's in the subnet mask represents the number of digits in the network address, and the number of 0's in the subnet mask represents the number of digits in the host address. Through the operation of the subnet mask, you can determine whether the hosts in the network are in the same subnet.

The method of filling in the subnet mask is as follows:

1. The subnet mask is usually represented by four decimal numbers, and the value range of each number is 0 to 255. For example, 255.255.255.0 is a common subnet mask.
2. In the subnet mask, 1 and 0 appear alternately, and the network address part is all 1, and the host address part is all 0. For example, in the subnet mask 255.255.255.0, the first three numbers are all 255, and the last number is 0, which means that the network address part is 24 bits and the host address part is 8 bits.
3. When filling in the subnet mask, generally speaking, the more digits the network address has, the fewer digits the host address has. For example, the common subnet mask 255.255.255.0 means that the network address is 24 bits and the host address is 8 bits, which is suitable for small networks; while 255.255.0.0 means that the network address is 16 bits and the host address is 16 bits, which is suitable for medium-sized networks. ; And 255.0.0.0 means that the network address is 8 bits and the host address is 24 bits, which is suitable for large networks.
4. The subnet mask needs to be filled in based on actual needs and network size. Generally speaking, if there are fewer hosts in the network, select more network addresses and fewer host addresses; conversely, if there are more hosts in the network, select more host addresses.

It should be noted that when filling in the subnet mask, different network devices and operating systems may have different representation methods. Some devices and systems use CIDR (Classless Inter-Domain Routing) notation, where the subnet mask is written directly after the IP address as part of the IP address, such as 192.168.0.0/24. The "/24" in this representation means that the network address has 24 bits and the host address has 8 bits.

To summarize, filling in the subnet mask needs to be selected based on actual needs and network scale. It is usually represented by four decimal numbers, in which the network address part is 1 and the host address part is 0. When filling in the subnet mask, you need to pay attention to the different representation methods of network devices and operating systems, such as CIDR notation. Correctly filling in the subnet mask is very important for normal communication and operation of the network, and should be carefully selected and filled in based on the actual situation.

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