Briefly describe the role of IP

IP address is a unified address format provided by the IP protocol. It assigns a logical address to every network and every host on the Internet to shield the physical address. difference.

IP addresses have been around for a long time, and have existed since the early days of the Internet. Users who want to access a website through the Internet can do so by directly entering the IP address.

Because IP is difficult to remember, it is slowly replaced by domain name if it is not used. However, this principle is still used for basic communication between computers. It is just by establishing a DNS service. DNS service The main function is to convert domain names into IP address access problems, which does not require people to remember addresses that are difficult to remember, and domain names are easy to remember.

Related recommendations: "FAQ"

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 is "0" and the address 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 network address The highest bit must be "10" and 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 is 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 address

starts with "llll0" and is reserved for future use.

The 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. Among the three main types of IP addresses, three areas are reserved as private addresses, which are more commonly used IP 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

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