How many categories are IP addresses divided into? How to distinguish IP addresses?

IP addresses are divided into five categories: Class A, Class B, Class C, Class D, and Class E. They are distinguished by the address ranges of these five classes of IP addresses.

1. Class A IP address

A Class A IP address means that among the four numbers in the IP address, the first number is the network number, and the remaining three numbers are The number is the number of the local computer. The length of the network identifier in a Class A IP address is 8 bits, and the length of the host identifier is 24 bits. The number of Class A network addresses is relatively small, with 126 networks, and each network can accommodate more than 16 million hosts.

Class A IP address address range 1.0.0.1 to 127.255.255.254.

2. Class B IP address

A Class B IP address means that among the four numbers in the IP address, the first two numbers are network numbers. The length of the network identifier in the Class B IP address is 16 bits, and the length of the host identifier is 16 bits. Class B network addresses are suitable for medium-sized networks. There are 16,384 networks, and each network can accommodate more than 60,000 computers. tower.

Class B IP address range 128.0.0.1-191.255.255.254.

3. Class C IP address

A Class C IP address means that among the four numbers in the IP address, the first three numbers are the network number, and the remaining number is is the number of the local computer. The length of the network identifier in a Class C IP address is 24 bits, and the length of the host identifier is 8 bits. There are more Class C network addresses, with more than 2.09 million networks. Suitable for small-scale local area networks, each network can only contain up to 254 computers.

Class C IP address range 192.0.0.1-223.255.255.254.

4. Class D IP address

Class D IP address was historically called a multicast address, that is, a multicast address. In Ethernet, a multicast address names a set of stations on the network that should receive a packet. The highest bit of the multicast address must be "1110", ranging from 224.0.0.0 to 239.255.255.255.

5. Class E IP address

Class E IP addresses start with "11110", and Class E IP addresses are reserved for future and experimental use.

Extended information:

The difference between IPv4 and IPv6:

The existing Internet runs on the basis of the IPv4 protocol, and IPv6 is the next version Internet Protocol, which can also be said to be the protocol of the next generation Internet, was originally proposed because with the rapid development of the Internet, the limited address space defined by IPv4 will be exhausted, and the lack of address space will inevitably hinder the further development of the Internet.

In order to expand the address space, it is planned to redefine the address space through IPv6. IPv4 uses a 32-bit address length, and there are only about 4.3 billion addresses, which are estimated to be allocated between 2005 and 2010, while IPv6 uses a 128-bit address length, which can provide almost unlimited addresses.

According to a conservative estimate of the actual addresses that can be allocated to IPv6, more than 1,000 addresses can still be allocated per square meter of the entire earth. In the design process of IPv6, in addition to solving the address shortage problem, other problems that were not solved well in IPv4 were also considered, including end-to-end IP connectivity, quality of service, security, multicast, mobility, and plug-in. Ready to use etc.

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