Explanation of the association between Intranet IP addresses and Internet access principles

First, explain the concepts of "intranet" and "Internet:

Intranet: the IP addresses of each computer in a LAN, for example, a School LAN, are mutually exclusive within the LAN. However, the Intranet IP addresses in the two local networks can be the same.

Internet: the Internet. The IP address is the only IP address that connects to the Internet through a server or a vro. That is to say, all computers in the Intranet are connected to this Internet IP address, and data is exchanged through this Internet IP address. That is to say, the Intranet IP addresses of all computers in a LAN are different, but they share one Internet IP address. (The IP address found using ipconfig/All is your local Intranet IP address. On www.ip138.com, you can see the IP address used to connect to the Internet, that is, the Internet ).

In the LAN, each computer can allocate its own IP address, which is only valid in the LAN. If you connect your computer to the Internet, your network provider (ISP) server will assign you an IP address, which is your Internet IP address. Two IP addresses exist at the same time, one internal IP address and one external IP address.

When you buy two computers in your house and want to build a LAN, you need to set up a fixed IP address for the two computers in addition to connecting the two computers with network cables, routers, and other devices, for example, if computer A is set to 192.168.1.2 and computer B is set to 192.168.1.3, you can use these two IP addresses to access each other, but these two IP addresses are only valid between the two computers, invalid for Internet. Therefore, the IP addresses allocated in the LAN have no correspondence with the IP addresses in the WAN.

When accessing the internet, your internal network machine sends a request to the gateway, and then the gateway (generally a router) forwards the request to the int network using the Internet IP address. After receiving the data, and then distribute it to your intranet IP address.

For example, the gateway is the door of your school. For the outside, your Internet IP is the door number of your school. But inside your school, you have several units, several floors, and several dormitories (intranet IP addresses ). What you want to send first goes through the school gate (GATEWAY ). The retrieved items are only written into the school room number (Internet IP address ). After receiving the goods, the portal room will be delivered to your portal according to the dormitory number (intranet IP address) of the apartment No. Of your dormitory. For example:

IP addresses on the Internet (Internet IP addresses) are centrally managed by an organization called "IANA" (internetassigned numbersauthority.

Due to unreasonable allocation and limitations of the IPv4 protocol, IP Address resources on the Internet are getting increasingly tight. To solve this problem, IANA retains part of class A, B, and C IP addresses, reserved for lan use

IP address space:

Class A Network

10.0.0.0 ~ 10.20.255.255

Class B Network

172.16.0.0 ~ 172.31.255.255

Class C Network

192.168.0.0 ~ 192.168.255.255

That is to say, if the IP address you find is within the range of A, B, and C, it must be the IP address of the LAN; otherwise, it is the IP address of the WAN.