Internet IP addresses are divided into several categories

What are the categories of IP addresses on the Internet?

IP addresses are divided into 5 types according to different network IDs, Class A addresses, Class B addresses, Class C addresses, Class D addresses and Class E addresses.

1. Class A IP address

A Class A IP address consists of a 1-byte network address and a 3-byte host address. The highest bit of the network address must be "0". Address The range is from 1.0.0.0 to 126.0.0.0. There are 126 Class A networks available, each of which can accommodate more than 100 million hosts.

2. Class B IP address

A Class B IP address consists of a 2-byte network address and a 2-byte host address. The highest bit of the network address must be "10 ”, the address range is from 128.0.0.0 to 191.255.255.255. There are 16,382 Class B networks available, and each network can accommodate more than 60,000 hosts.

3. Class C IP address

A Class C IP address consists of a 3-byte network address and a 1-byte host address. The highest bit of the network address must be "110". The range is from 192.0.0.0 to 223.255.255.255. There are more than 2.09 million Class C networks, and each network can accommodate 254 hosts.

4. Class D addresses are used for multicast (Multicast).

The first byte of the Class D IP address starts with "lll0", which is a specially reserved address. It does not point to a specific network. This type of address is currently used in multicast (Multicast). A multicast address is used to address a group of computers at a time and identifies a group of computers that share the same protocol.

5. Class E IP addresses

Start with "llll0" and are reserved for future use. An all-zero ("0.0.0.0") address corresponds to the current host. The IP address with all "1"s ("255.255.255.255") is the broadcast address of the current subnet.

Extended information:

In the three main types of IP addresses, 3 areas are reserved as private addresses. The address range is as follows:

Class A address: 10.0.0.0～10.255.255.255

Class B address: 172.16.0.0～172.31.255.255

Class C address: 192.168.0.0～192.168.255.255

The first group of numbers in a Class A address is 1 to 126. Note that the numbers 0 and 127 are not used as Class A addresses, the number 127 is reserved for the internal loopback function, and the number 0 indicates that the address is the local host and cannot be transmitted. The first set of numbers for Class B addresses is 128 to 191. The first set of numbers for a Class C address is 192 to 223.

1. Class A address

The representation range of Class A address is: 0.0.0.0~126.255.255.255, the default network mask is: 255.0.0.0; Class A address is allocated to special scale Large network usage. Class A networks use the first set of numbers to represent the address of the network itself, and the next three sets of numbers as the addresses of hosts connected to the network. Assigned to large networks with a large number of hosts (direct individual users) and a small number of LANs.

2. Class B address

The representation range of Class B address is: 128.0.0.0~191.255.255.255, and the default network mask is: 255.255.0.0; Class B address is allocated to general Medium sized network. Class B networks use the first and second sets of numbers to represent the network address, and the last two sets of numbers represent the host address on the network.

3. Class C address

The representation range of Class C address is: 192.0.0.0~223.255.255.255, and the default network mask is: 255.255.255.0; Class C address is allocated to small networks , such as general local area networks and campus networks, the number of hosts that can be connected is the smallest, and the users are divided into several network segments for management.

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