6.5. Internet Addressing and Protocols

A host is a computer connected to the Internet. Identification of each host in the network is carried out through two systems of addresses, which always act together.

Like the phone number, the IP address is assigned by the provider and consists of four bytes, separated by dots and ending with a dot. Any computer on the Internet must have its own IP address.

In the domain name system, DNS names are referred to as a provider. Such a fully qualified domain name like win.smtp.dol.ru includes four simple dots separated by dots. The number of simple domains in a fully qualified domain name is arbitrary, and each simple domain describes some set of computers. At the same time, the domains in the name are nested in each other. Fully qualified domain name must end with a dot.

Each domain has the following meaning:

• gu - country domain, denoting all hosts in Russia;

• dol - provider domain, denoting computers of the local network of the Russian company Demos;

• smtp - the domain of the Demos server group that serves the email system;

• win is the name of one of the computers in the smtp group.

Of particular importance are the top-level domain names, located in the full name on the right. They are fixed by the international organization InterNIC, and their construction is carried out on a regional or organizational basis.

The URL addressing system is used to specify how information is organized on a particular host and to identify the information resource placed on it. For example, a URL can be written as follows: http://home.microsoft.com/intl/ru/www_tour.html. The elements of this address entry denote:

• http: // is a prefix that indicates the type of protocol that indicates that the address belongs to a host that is a WWW server;

• home.microsoft.com - domain name of the host. A colon after the domain name may contain a number indicating the port through which the connection to the host will be made;

• / intl / ru / - subdirectory of the root directory intl of the host;

• www_tour.html - file name (file extension can include any number of characters).

Memorizing a long URL is difficult, so all Internet tools have a Favorites tool. Existing online tools provide convenient conditions for creating, storing and using links. Among them are:

• the presence of a special Favorites folder. It exists in all programs of work with WWW, in it you can create nested thematic folders. Examples of such folders can be, in particular, Banks, Socio-economic indicators, Analytical forecasts;

• the introduction of tool buttons in the toolbars of work programs in the Internet to use the most popular links;

• location of links or their shortcuts directly on the desktop or in the taskbar;

• Automatic transfer of links from the Favorites folder to the Favorites menu item that occurs when you click the Start button.

To identify the recipient of the e-mail system is used E-mail-addresses. This address must not contain spaces.

Addressing in the news system is similar to addressing using a domain name. Each group of characters, separated by dots, forms a theme. Each topic in the conference name, like the DNS, is a collection of some set of articles.