IP Address Identification and composition and Classification

An IP address is the binary number of a computer in a 32-bit network.

1. marking method.

There are two identification methods: Binary Notation (within the computer, each 8-bit segment, a total of 4 segments) and decimal notation (each segment is converted to decimal format ).

2. composition method.

An IP address consists of a network IP address and a Host IP address. The network IP address mainly indicates the network number of the network in which the host IP address is located, and the Host IP Address indicates the numbers of different computers in the network.

3. IP classification.

① Category A address: the first address is 0, and the IP address range is 1.0.0.1 ~ 126.255.255.254, the first segment is the network number (126 network numbers in total), and the third segment represents the host number (each network can accommodate 2 ^ 24-2 hosts), which is applicable to ultra-large networks.

② Class B address: the first two digits are 10, and the IP address range is 128.0.0.0 ~ 191.255.255.254, the first two groups are network numbers (64*256 = 16384 network numbers in total), and the last two groups represent host numbers (each network can accommodate 2 ^ 16-2 hosts ), suitable for medium-sized networks.

③ Class C address: the first three digits are 110, and the IP address range is 192.0.0.1 ~ 255.255.255.254, the first three groups of network numbers (a total of 2 ^ 21 = 2097150 network numbers), the last group of master machine numbers (each network can accommodate 254 hosts), suitable for small networks.

④ Class D address: the first four digits are 1110 and the IP address range is 224.0.0.1-239.255.255.254. It is a multicast address.

⑤ Class E address: the first five digits are 11110 and left as backup.

4. Special IP address.

When ① All host numbers are 0: indicates the network number, and hosts cannot be allocated.

② When the host number is all 1, it indicates that the broadcast is sent to the specified subnet.

③ 255.255.255.255: the subscriber's intranet broadcast address.

④ 127. x: Test address, which is not assigned to the host. 127.0.0.1 to 127.1.1.1 is used for loop testing.

5. The IP address range reserved by INTERNIC (private address, which belongs to a non-registered address and is specially used within the Organization ).

Class A: 10.0.0.1 ~ 10.20.255.254.

Class B: 172.16.0.1 ~ 172.31.255.254.

Class C: 192.168.0.1 ~ 192.168.255.254

This type of IP address is generally used when we build a LAN.