Test and development of network articles-IP address

Here is an introduction to the currently widely used version of IPv4.

The IP address uses a unified format to assign a logical address to every network and every device on the Internet. The IP address is a 32-bit binary number. For easy viewing, it is usually divided into 4 groups. The 8 bits of each group are expressed by a decimal number to form an address in the form of 192.168.0.10.

The IP address consists of two parts, a network ID and a host ID . The two parts are distinguished subnet mask Therefore, a complete IP address must include the host address and the subnet mask . It can be expressed in the following two forms:

1. 192.168.0.10 host address and 255.255.255.0 subnet mask : When configuring the network address in Windows, you will be required to enter these two values at the same time;
2. 192.168.0.10/24: the binary digits of the 160fa7ee19403b subnet mask 160fa7ee19403d. The corresponding decimal grouping is expressed as 255.255.255.0. There are 3 decimal 255s displayed here, and the simple conversion relationship is 24 (binary digits) / 8 (8 digits per group) = 3 (number of groups).

a binary AND operation on the host address and the subnet mask network ID . If you are not familiar with binary arithmetic, you can simply mask the corresponding mask part of the IP address as 0. For example: IP address class C 192.168.1.10, use subnet mask 255.255.255.0 to shield the fourth group, get the network ID where the host is 192.168.1.0.
It should be noted here that the value of each group of the subnet mask does not have to be exactly 255 or 0. 255.255.12.0 is also a legal subnet mask .

People have defined three types of addresses, A, B, and C. The subnet masks are as follows.

• Class A: 255.0.0.0
• Type B: 255.255.0.0
• Type C: 255.255.255.0

A range of private IP addresses is also defined, specifically for internal use by organizations.

• Type A: 10.0.0.0~10.255.255.255 ie 10.0.0.0/8
• Type B: 172.16.0.0~172.31.255.255 ie 172.16.0.0/12
• Type C: 192.168.0.0~192.168.255.255 ie 192.168.0.0/16

These are also the addresses you see the most in the company. Different organizations can use the same private address. This is because the internal network of the enterprise is isolated from the Internet and forwarded through routers. The private address is not directly exposed to the public network.

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