What does network prefix length mean?

Network prefix length network prefix, the part of the IP address corresponding to the network part of the address, is used to uniquely identify the network number of a network connected to the Internet, called the network prefix.

#The operating environment of this article: Windows 7 system, Dell G3 computer.

1. Network prefix network prefix:

The part of the IP address corresponding to the network part of the address; for example, the network prefix of a Class B address is /16 (that is, the first 16 bits represent the address The network part, and 255.255.0.0 is the corresponding default subnet mask

The network number used to uniquely identify a network connected to the Internet is called the network prefix.

2. For standard Class A/B/C addresses, the network prefix is ​​fixed 8, 16, and 24 bits. The network prefix 20 mentioned in the title is an address subdivision strategy that uses the CIDR concept.

3. CIDR The original classful routing process used to allocate Class A, Class B, and Class C addresses has been restructured. CIDR replaces the original address structure's restriction on the network portion of the address (Class 3 addresses) with a 13-27-bit long prefix. The network portion is limited to 8, 16, and 24 bits respectively). The number of hosts in the address block that the administrator can assign ranges from 32-500,000, thus better meeting the special address needs of the organization.

The CIDR address contains the standard 32-bit IP address and information about the number of network prefix bits. Take the CIDR address 222.80.18.18/25 as an example, where "/25" indicates that the first 25 bits in the previous address represent the network part , the remaining bits represent the host part.

4. Therefore, the network prefix in the question is 20, which means that a Class B address (standard network prefix 16) is subdivided into more subnet segments, and the network prefix increases to 20.

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