What is a virtual host

Virtual host is a method of implementing multi-domain services on a single host or host group. It is a technology that can run multiple websites or services. Virtual hosts are completely independent and can be managed by users themselves. It does not mean that it does not exist, but it means that the space is extended by physical servers, and its hardware system can be based on a server group or a single server.

Its technology is a technology used by Internet servers to save server hardware costs. Virtual host technology is mainly used in HTTP, FTP, EMAIL and other services. One or all of the service content of a server is logically divided into multiple service units, which are externally represented as multiple servers, thereby making full use of server hardware resources. If the partitioning is at the system level, it is called a virtual server.

Definition

Virtual host, also called "website space", is to divide a physical server running on the Internet into multiple "virtual" servers. Virtual host technology has greatly promoted the application and popularization of network technology. At the same time, virtual host rental services have also become a new economic form in the Internet era.

Background

There are nearly 100 million computers connected to the Internet. No matter what model they are, what operating system they run, or what software they use, they can all be attributed to two Major Categories: Clients and Servers.

Client: The client is a machine that accesses other hosts. When accessing the Internet through an ISP (Internet Service Provider), the client is assigned a temporary IP address. Using this temporary IP address, the client can obtain information from the Internet network. After the network is disconnected, the client The computer is disconnected from the Internet and the IP address is recovered.

Server: Server refers to computers with high computing power that can be used by multiple users, usually also called hosts. There are many differences between servers and clients. For example, a client usually only serves one user at a time. The client is used by users through the terminal, and the server is used by client users through the network. Compared with the client, the server needs to work continuously in a 7×24 hour environment. This means that the server needs more stability technologies RAS (Reliability, Availability and Serviceability, reliability, availability, applicability), such as supporting the use of ECC (Error Check and Correction, error checking and correction) memory.

Technical Features

Virtual host technology is a technology used by Internet servers to save server hardware costs. Virtual host technology is mainly used in HTTP (Hypertext Transfer Protocol, hypertext transfer) Protocol) service logically divides one or all of the service content of a server into multiple service units, which are externally represented as multiple servers, thereby making full use of server hardware resources.

Virtual host uses special software and hardware technology to divide a real physical server host into multiple logical storage units. Each logical unit has no physical entity, but each logical unit can work on the network like a real physical host, with a separate IP address (or shared IP address), an independent domain name, and a complete Internet server (support WWW, FTP, E-mail, etc.) functions.

The key technology of virtual hosting is that even if different server programs opened for multiple users are running on the same hardware and the same operating system, they will not interfere with each other. Each user has his own part of the system resources (IP address, document storage space, memory, CPU, etc.). Each virtual host is completely independent from each other. To the outside world, each virtual host behaves exactly the same as a separate host. Therefore, this virtualized logical host is vividly called a "virtual host".

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