英语作业课文翻译

The Internet

The most famous example is the Internet internet. The Internet originated in the nineteen sixties initial research project. Its goal is to develop a kind of ability, the computer connected to the network, enabling them to act as a not for local disaster and collapse of the interconnected system operation. The initial work is mostly by the United States government through the Department of Defense Advanced Research Projects Agency launched. As the years passed, the Internet 's development from a national defense project into a research project. Today, it is largely a commercial project, connecting with the world wide area network, metropolitan area network and local area network, involving millions of computers.

One, the Internet Architecture

Conceptually, the Internet can be viewed as the set of fields. Each domain is represented by a network or a relatively small Internet component, like university, by a company or government agency that is responsible for operation of the organization. Each domain is a independent system, according to the local authority desire configuration. It may be produced by a computer or a contains many metropolitan area network, wide area network, even the complex Internet. Field created by the Internet Corporation for Assigned Names and numbers ( ICANN ) supervision. It is a non-profit company, which was established to coordinate the domain name and IP address allocation. To be on the Internet to build a domain, the domain must first pass through a ICANN authorized to do this work, known as the domain name registration services company registration.

A domain once registered, namely can use a router connected to the existing internet. The router will be the domain in a network and has been on the Internet within a network connection. This particular router is often referred to as the domain of the gateway, because it is equivalent to the domain to the Internet the

remaining portion of the gate. From the perspective of a single domain, located at the gateway out of that part of the Internet is sometimes called the " cloud ", which refers to the following facts: the Internet Gateway outside structure that is not under its control, and its operation is no relationship. Transfer to a destination within the domain of any message in the domain processing, transmission to the outside of a destination any message is first sent to the gateway, and then by the gateway sends out into the clouds.

If a person " station " in a domain gateway " outward looking " cloud, you will find a variety of structure. Indeed, with the domain to find and establish a connection point cloud, the Internet also to a casual way of development. However, a popular structure, some domain gateway connected together, formed by a gateway regional network. For example, a group of university can choose to focus its resources, for the construction of such a network. The regional network and then connected to a larger network, the latter which is also connected with other regional network. Thus, the parts of the cloud assumes a hierarchical structure ( Figure 9A-1 ).

In two, connecting to the Internet

In order to simplify the process of connecting to the Internet, many called the Internet service provider companies allow customers through the company's equipment to their domain to connect to the Internet, or have become the company has established a domain part. With the Internet service provider 's economic connection is perhaps through temporary telephone link established connection, this connection is called a dial-up connection. Using this method, a personal computer connected to the local telephone line, and then run a software package, the Internet service provider computer sends out a call. At this time, Internet service providers to provide Internet access services, continuous time to call time length. The temporary connection model in mobile phone / computer domain ( actually more popular application more and more ). However, in a fixed

position in the temporary connection application, fast in permanent connection, this connection via DSL, cable television lines and satellite links are relatively high system bandwidth. These techniques greatly reduces the broadband Internet access ( mass ) ( once available only to afford dedicated Internet connection of large institutions ) costs, so that home users can visit today's multimedia applications.

At the family level there is another development, home computer system from single computer equipment expanded into a plurality of computer network, the network are usually implemented as Ethernet bus network. These networks using a home router access the Internet, and the router through the digital subscriber line, cable television line or a satellite link with internet service providers to permanently connected, thus allowing the system to become a home Internet service providers to establish a domain in local network. From home to home local network router computer connection often adopts a wireless mode. That is to say, each computer to use a distance of about 100 feet of small transmitter / receiver and communications router. The wireless local area network outside the home is also very popular, being used for establishing the