Internet naming rules and address demarcation conventions

For our average user, the symbol of visualization is much better than a bunch of boring digital coding. For example, we will easily remember the string "www.oscar.com", but it is difficult to remember 206.17.191.12. This article briefly introduces the Convention of Internet naming rules and addresses, then describes how to use the Java language to complete the conversion between the symbol name (the string above) and the IP address (above the number string), and gives an instance of the remote host to check for access.

Internet naming rules and address demarcation conventions

On the Internet, the symbol name (symbolic name) is used to name the host and network, such as www.oscar.com. The "scientific name" of these symbolic names is called "Domain name". Although domain names are much more convenient for us, they must be converted to IP addresses (Internet Protocol address) before they can be used as communication identities. An IP address is a 32-bit identifier that includes a network identity and host identity to uniquely identify the host and network. Domain name conversion to IP address work is done by a dedicated system, this is the domain Name System?? DNS).?

When data is sent/received between the same network or different network hosts, the IP address begins to function. If the data is passed between hosts in the same network, only the host identity in the IP address is used to determine where the host is located on the network. On the other hand, if there is communication between hosts in different networks, the host identity and network identity are used to determine the corresponding host. The process of locating networks and hosts, and then data transfer, is called Routing (routing). The routers in the network (router) contain an IP layer (IP layers), which is responsible for executing the routing algorithm that sends packets to the destination. On the Internet, sending the database to the destination is within the IP layer.

IP address is the Internet registration Department?? Network Information Center (web Information Center?? NIC) is assigned to different organizations, and the organizations are delegated to multiple departments. The IP address takes up to 4 bytes.

Routed packets may also be lost during the transfer process. As a result, people use the underlying transport protocol to determine whether or not data is transmitted correctly. For example, TCP is used to check for errors or data loss, and when an error occurs, the corresponding database is sent again until the other host is properly received.

Currently, there are 3 categories (or 3 levels) of IP addresses: Class A, Class B, and Class C. In addition, there is a class of IP addresses called "multicast" that are used on some Internet hosts. These different categories of IP addresses meet the needs of different organizations. For example, a Class A address is mainly used for large network systems with more than 65536 hosts; The Class B address is used for medium-sized network systems with a host number greater than 255, but less than 65536; Class C addresses are used for small networks where the number of hosts is less than 256.

The above describes the Internet naming rules and address division conventions, including aspects of the content, I hope that the PHP tutorial interested in a friend helpful.

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