What domains exist. Domain - what it is and how the domain name system works. Cyrillic domains and their distinctive features

Many dummies have terrible confusion in their heads regarding concepts such as “domain”, “domain name”, “site domain”, “server domain” etc. What is this? Are they all the same thing or completely different things? You can read many definitions of these concepts on the Internet. Some argue that a domain is a domain name, because it is the name of a website. Others write that the domain is site name, and the domain name is Website address. In short, complete confusion! Everything may be clear to advanced users, but for beginners there is no clarity at all.

Let's figure out these concepts together so that everything settles into place in our brains, once and for all!

We will assume that you have read the article “How the Internet Works” and know that, as a rule, sites are hosted on the disk space of Internet servers of hosting companies.

All computers on the network, including host provider servers, have their own IP address, which is a sequence of numbers. So, to find any site on the World Wide Web, you need to know the IP address of the server where the site is located.

However, there can be many different websites on the same server or different IP address. How to be? To make searching easier it was invented Domain Name System(DNS – Domain Name System). This alternative addressing system is more understandable to humans. You give your site a unique name, or in another way, Domain name.

Domain name- this is a unique combination of characters of the Latin alphabet, by which you can identify your site among many others. In addition to letters, a domain can include numbers from 1 to 9 and the hyphen symbols “-”, but a hyphen cannot appear at the beginning or end of the domain. The domain length can be from 2 to 63 characters.

Next, you host your website on a server with a specific IP address. In order to match the symbolic domain name of your website to a specific digital IP address, there are special DNS servers.

DNS server- a program that converts a domain name into a digital IP address and vice versa. The memory of these servers stores extensive tables in which each domain name is assigned an IP address. Remember that one IP address can correspond to many domain names!

Every time you type a domain name into your browser, the DNS service calculates what IP address the name corresponds to and what resource it needs to serve to you. Therefore, the domain name of a website is often called the domain address of the website or the domain name of the server, etc. In essence, they are all the same thing.

A person is much more comfortable using domain names than digital IP addresses.

However, the unique and complete address of the site is its URL(Uniform Resource Locator), which consists of three main elements: Protocol + Domain Name + Path/File. As you can see, a site's domain name is only part of its full Internet address.

Each domain name consists of several parts separated by dots - these are domains of different levels. The number of domain levels is usually limited to two or three. A long domain name and a large number of domain levels are inconvenient to use. The rightmost field is called Top level domain, then, from right to left, the names of lower-level domains follow.

Top level domains

Top level domains are also called domain zones. For example, in the domain name the site , . ru is a top-level domain.

All top-level domains can be divided into two groups:

National or geographic domains, they determine whether a site belongs to a particular country or geographic territory. For example, the domain .ru belongs to Russia, .kz to Kazakhstan, .ua to Ukraine, etc.

Public Domains. They can establish that the site belongs to a certain category or type of activity. For example, .com - commercial, .info - informational, .biz - for business, .org - non-profit, .travel - tourism, etc.

The basis for the Russian Internet zone (Runet) is the domain . RU. It is this that makes it possible to register various domain names for the Runet due to the emergence of second-level domains.

Second level domains

The name of my website blondinka-net.ru is a second-level domain name. Here .RU is a top-level domain. Own name of the website – likbez-net is in second place from the end of the full name. That is why such domains are called second-level domains.

The second and all subsequent domain levels have an important limitation - they must be unique within the group of their parent domain. In other words, there can only be one second-level domain on the Internet likbez-net in the top level domain . ru .

Second level domain names are registered with registrar organizations.

It should be noted that the right to own a second-level domain is issued to an organization or person only for a year; the application must be renewed for each subsequent year.

Third level domains

Third level domains are registered with organizations that own second-level domains.

The owner of a second-level domain has the opportunity to create an unlimited number of addresses of the third and further levels. So, for example, I, as the owner of a second-level domain website, I can create a domain for the forum forum.likbez- net. ru. The result was a third-level domain name, and forum is a third level domain in the zone likbez- net. ru.

Typically, the third-level domain registration service is provided by providers– internet service providers .

What is a domain? This question is asked by almost every novice Internet user. Without going into details, the answer is quite simple. A domain is the name of a website on the network, unique and unparalleled. You can view the domain on which the page you are currently viewing is located in the address bar of your browser. Everything that comes after these letters is the path to this article.

In fact, website addresses have numerical values ​​that are very difficult for users to remember. But now that the domain name system has been developed, each site creator can assign it an easy-to-pronounce and remember name, which makes navigating the Internet more convenient.

Domains are usually divided into several levels. Each level is determined by how many dot-separated parts there are in the name. For example, a first-level domain is nothing more than a zone on the Internet. Websites are not located on 1st level domains.

Examples

• .ru – Russian
• .ua - Ukrainian
• .com – Commercial
• .org – Nonprofit Organizations
• .edu – Educational Resources
• .gov – Government
• Other options (more than several dozen)

Second-level domain – denotes the name of a resource within one of the domain zones. For example, our Businesslike forum is now located on a second-level domain, where Businesslike is the name of the site, and a.ru is the zone in which it is located.

Third-level domain – determined by the name of the resource within the second-level domain. Name. Second level name. Domain zone. As a rule, 3rd level domains are absolutely free. Take, for example, the website builder Ucoz, known to many webmasters, which gives clients domain names like site.ucoz.ru; site.at.ua and the like.

A fourth-level domain is a fairly rare phenomenon on the Internet. They are built on exactly the same principle as the previous domain levels, only the name becomes even longer. For example: video.site.hosting.ru.

Which domain name to choose: 2nd or 3rd level

Now that you have an idea of ​​what the second and third levels are, you will probably want to know which one is best for your future website. Let's try to figure it out.

Top level domains: general and limited use

Popular general purpose top-level domains

Examples of restricted top-level domains

More details:

http://www.icann.org (English)

http://www.iana.org (English)

Root domain(eng. root domain) - the top-level domain in any domain name system.

Internet root domain ( zero-level domain) is served by domain name system root servers located in various countries around the world.

In the Internet DNS system, the root domain is designated by a blank (that is, does not contain any characters) name.

When writing a domain name, each domain is separated by a dot.

There may be a period at the end of the name that separates the empty name corresponding to the root domain. If this dot is present (for example, “www.site.”), then the domain name is considered fully qualified (absolute).

If there is no dot at the end of the name ("www.antula" or "www..

Every Internet application (browser) must handle the trailing dot correctly. But most of them allow you to enter a domain name without a period at the end. The handling of such names is implementation dependent. In the simplest case (if, for example, in the context of a given application it is impossible to determine in relation to which base domain the address is given), a trailing dot will be added to the address and it will be treated as absolute.

Sometimes, to obtain a fully qualified domain name, local software (operating system, application, etc.) can attach to the relative name a certain default domain, which is determined by the domain name of the computer, or can be specified in the settings.

Sometimes several such domains can be specified in the settings, which are searched in turn until a name that exists in the DNS is found.

For reference

ISO 3166 is an international ISO standard that defines the code designations of states and dependent territories, as well as the main administrative entities within states. Consists of the following parts:

ISO 3166-1 - codes of states and dependent territories.

ISO 3166-1 alpha-2 - two-letter.

ISO 3166-1 alpha-3 - three-letter.

ISO 3166-1 numeric - digital.

ISO 3166-2 - codes of administrative entities within states (regions, states, provinces, etc.)
ISO 3166-3 - codes of states that no longer exist (merger, division, change of name, etc.)
ISO 3166-1 alpha-2 two-letter codes are used by ICANN to assign country code top-level domain names.

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A first-level domain (English top-level domain, TLD) is the very last word in the site address, indicating affiliation with a country or organization, due to which the search area becomes narrower.

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All first-level domains can be divided into two groups:

• Territorial (regional, national) - ru, ua, us, de, su, rf, rus and others - are assigned to each state.
• Thematic (general) domains - org, com, net, info, biz and others - are first-level domains of general use and are not subject to restrictions related to territorial location.

If you try to explain in simple words what is a first-level domain in the address, it will turn out something like this. Suppose we need to send a letter to some place, which is located in some city, in some country. In order for the letter to reach the addressee, the exact address and name of the recipient are needed.

On the Internet, such an address will look something like this: www.l-grad.spb.ru. Where www is the designation of the Internet, l-grad is the desired location, spb is the city of St. Petersburg, and ru is the first-level domain assigned to Russia.

Differences from other levels

First-level domains indicate belonging to a particular country or topic. - the name of the site, its name, which is registered in one of the domain zones. The third level is a subdomain, which is, as it were, attached, located under the second level, denoting its section.

Top-level domain names cannot be used as an address. They are needed for second level registration. That is, you can register a second-level domain on the top-level domain. For example: site.ru is the second level.

The third level - forum.site.ru, for example - is created on the basis of a second-level domain.

That is, all subsequent levels are created on the basis of the previous one. And, in fact, they are subdomains or subdomains. These are additional site structures: blogs, forums, etc.

First level domain names have already been created, users cannot register them themselves and give an original name. But for the second level, you can come up with and register any name, as long as it is free.

Examples of first-level domains in tables

Are common

• .com, .biz - commercial organizations and businesses
• .travel - tour operators and agencies
• .net - networks and telecommunications
  .post - postal organizations
• .org - non-profit organizations
  .museum - museums
• .mil - military organizations
• .invalid - invalid pages
• .aero - aviation organizations
• .test - for tests

Territorial

• .au - Australia
• .es - Spain
• .az - Azerbaijan
• .eu - European Union
• .be - Belgium
• .fr - France
• .by - Belarus
• .it - ​​Italy
• .ca - Canada
• .ru - Russia
• .ch - Switzerland
• .se - Sweden
• .cn - China
• .uk - UK
• .de - Germany
• .us - USA

We found:

• that the first level domain is the short word at the end of the address after the period;
• that first-level domains indicate belonging to a domain zone - geographical or thematic;
• that anyone can register a website on almost any open domain, regardless of their place of residence.

When choosing a name for a site, users are faced with another new concept - the domain level. Some say that the third level is bad, others confuse the first with the second. How to correctly determine the levels, and which domain is not liked by search engines? Let's look at the main points.

The following domain classification is commonly used:

First level- these are domains tied to a territory ( rf, ru, ua) or topic ( org, biz, info). These domains are not for sale, as they are distributed between certain zones in which you can register a site.

Second level- a unique part of the address that stands before the first-level domain and is separated from it by a dot. In the address website the second level domain is the name " konstruktorysajtov" Its uniqueness lies in the fact that a second-level domain is registered on one web resource and cannot be used on another site.

Third level- a resource within a second-level domain. site.ucoz.ru- an example of a third-level domain.

Typically, the third level is used when creating a web resource on a site builder or placing individual sites inside a large portal - for example, forum.site.ru. Strictly speaking, www.site.ru- this is also a third-level domain; the second level will be site.ru. Therefore, optimizers advise specifying the address without WWW, since technically www.site.ru is a subdomain site.ru.

There are several features in the definition of a third-level domain. In some countries, there were no second-level domains by definition before: for example, in the UK, until 2014, domain names were used in this form: org.uk, com.uk etc., that is, technically this is already the third level. In this case, the classification shifts one level: forum.site.com.uk will already be a fourth-order domain.

Is level three so bad?

Third-level domains are not held in high esteem by webmasters, but there are no facts proving their inconsistency when promoting a website. Search engines don't pay attention to the domain level. If the site meets certain requirements (domain level is not among them) and contains unique, interesting content, then search engines will return pages of your site in search results, regardless of whether the domain has a second or third level.

Website visitors are not at all interested in the domain level - the main thing is that the address can be remembered and reproduced. But third-level domains are also different. It's one thing if you have site.org.ru- no one will pay attention to the fact that there are some extra words in the address. It’s a different matter if you created a website using a free builder like