Addressing the Internet: the types and principles of building
In order to identify each specifica computer connected to the Internet, a special addressing system was developed. There are two types of Internet addressing: numeric (IP addressing) and symbolic. These two systems exist in parallel. Numeric addressing is used by machines, symbolic by people. After all, it is much easier for a person to memorize and interpret symbols (letters) than numbers.
Any computer connected to the Internet hasIP address (short for Internet Protocol), which consists of four numbers separated by dots (XXX.XXX.XXX.XXX). The information presented in this form completely identifies the address of the computer. Each number varies from 000 to 255. This addressing on the Internet is sufficient to encode four billion computers.
While the World Wide Web had a smallthe number of subscribers, digital system was quite enough, but with its expansion to use such a model it became inconvenient. And it was decided to use the domain name system DNS (from the English Domain Name System) in parallel. For this purpose, a certain group of people was responsible for assigning unique names to users in a certain segment. There is no Internet control center in the world, but there are organizations that check and assign numbers: the domain name of the computer must be unique, and these organizations follow this. Addressing the Internet using domain names is today the most widespread.
The computer name can contain any number ofdomains, but the majority contains from two to five titles, which are separated from each other by a dot (for example, tvka.ivno.ru. or www.companys.com). Such addresses have some analogy with postal ones. To send a message to the right person, first indicate the country, then the region, the district, the locality, the street and the name itself. A similar hierarchy is also addressed on the Internet: on the right is the domain of the first (higher) level, followed by lower-level domains that all together and create a unique computer name. The top-level domain name on the right usually carries information about the geographical position of the computer (.ru - Russia, .by - Belarus, .ua - Ukraine, etc.) or the topic that the site (.gov - governmental structures; .com - commercial organizations; .org - non-profit organizations; .edu - educational institutions, etc.). But site owners do not always adhere to the accepted classification, and in the .RU zone there may well be a Belarusian, Kazakh or any other site.
There are so many addresses on the Internet thatIt is impossible to imagine a database that could contain all the addresses, so a protocol has been developed that searches for the given name. To do this, a special program is installed on the provider's server, in which the character DNS addresses are converted to an IP address. Then, the server is searched for, where information about the required site or mailbox is stored. In fact, this is a very difficult task: there are too many servers on the network. To simplify the search, use universal URL resource pointers (from Universal Resource Locator). Such a pointer contains information about the protocol that must be used to find the address, the search program and the file containing the necessary information, which makes the search for a particular site much easier.