Every device on the Internet has an IP address, because the existence of IP addresses can only be interconnected and data transmission can be carried out. By definition, an IP address refers to an Internet Protocol address, which is also translated as an Internet Protocol address. It is the logical address of the device after it is connected to the network. The IP address consists of 4 segments of data, each segment of 1 byte and 8-bit binary numbers.
At the beginning of the Internet's design, in order to facilitate searching for web addresses and hierarchical construction of the network, each IP address included two identification codes (IDs), namely network ID and host ID. All hosts on the same physical network use the same network ID. A host on the network (including workstations, servers, routers, etc. on the network) has a host ID. The Internet Council has defined five IP address types to suit networks of different capacity, namely Class A to Class E. Among them, three types A, B, and C are uniformly allocated globally by InternetNIC (International Internet Network Information Center) and are the three commonly used types of IP addresses; classes D and E are special addresses.
1. Class A IP address
For Class A IP address, the first segment of one-byte data represents the network number, and the remaining three segments represent the host number. If the highest bit of the network number must be 0, it can represent 0000 0001- 011111, that is, 126 (excluding all 0s and all 1s) networks, and the remaining 3 bytes of data can represent 2^24-2 hosts. Class A subnet mask 255.0.0.0. It is mostly used in large organizations or institutions, such as government and military institutions, large research institutions, etc.
2. Class B IP address
For a Class B IP address, the first two segments of 2 bytes of data represent the network number, and the remaining two segments represent the host number. It is stipulated that the highest bit of the network number must be 10, so the range is from 10000 0000-10111111, that is, 128-191, and the address range is from 128.0.0.0-191.255.255.255. There are 2^14-2 networks, which can accommodate 2 to the 16th power-2 hosts. Subnet mask 255.255.0.0. It is mostly used in medium-sized organizations or companies, such as university campuses, educational institutions, research laboratories, and medium-sized companies. For example, a college campus network with thousands of devices might choose to use Class B addresses to manage its internal network.
3. Class C IP address
For a Class C IP address, the first three paragraphs of 3 bytes represent the network number, and the remaining paragraph represents the host number. If the highest bit of the network number must be 110, the range is from 1100 0000-1101 1111, that is, 192-223, which can represent 2^21-2 networks and can accommodate 254 hosts. subnet mask of 255.255.255.0 It is mostly used by small organizations or individuals, such as small businesses or home networks. And because of their abundant host address space and ease of management, they are also often used in branch offices or remote sites to ensure smooth communication between local devices.
4. Class D IP address
Class D IP addresses range from 224.0.0.0-239.255.255.255. They do not distinguish between network bits and host bits, and do not have a subnet mask in the traditional sense. Mainly used for multicast, allowing one or more senders (sources) to transmit information to multiple recipients (destinations). Multicast is an efficient communication method that is especially suitable for multimedia applications and real-time data transmission.
5. Class E IP address
The range of Class E IP addresses is from 240.0.0.0- 255.255.255. Class E addresses have no fixed network bit and host bit division, and have no subnet mask in the traditional sense. It is mainly used for experimental and research purposes, such as scientific research and development, experimental networks, etc., and is generally not used for commercial networks. And such addresses are rare in actual network deployments because they are not formally assigned to any specific purpose.
