DNS name servers. What is DNS and how DNS servers ensure the Internet works

Computers on the network (including the Internet) do not have names; data transfer is carried out using IP addresses.

IP address(Internet Protocol Address) - a numeric address on the Internet, looking like 123.123.123.123. IP addresses are difficult for humans to remember, especially when you visit dozens of sites a day with different IP addresses.

Similar to how you save phone numbers, you can keep a contact book or phone directory for IP addresses. Role telephone directory perform on the Internet DNS(Domain Name System), domain name system. When you enter something in an Internet browser domain name, it is converted via DNS into an IP address, which is used to access the server.

In fact, DNS servers store not only the IP address of the server, but also other data such as DNS resource records “MX”, “TXT”, “A”, “CNAME”, “SOA”.

DNS servers, which store information about thousands or millions of domains, are often hosted on separate, powerful servers. In such cases, the expression “DNS server” can mean the entire software and hardware complex (server and program itself).

Why register DNS servers for a domain?

When you register a new domain name, no DNS server on the Internet knows about it. And until information about your domain appears on the Internet DNS servers, neither the website, nor the mail, nor any other services will work.

In order for DNS servers on the Internet to know about your domain, someone must tell them, and this someone is the DNS server that you register for your domain. It plays the role of a “herald” who always keeps the latest information about your domain. For example, the hosting DNS servers ns1.hosting.site and ns2.hosting.site store information about domains that are connected to the hosting site.

About the differences between DNS servers ns1.hosting..hosting.site And ns1..site and read about which of these pairs is right for you.

DNS servers are registered in pairs, this is done for better fault tolerance: if one DNS server fails, the other will remain working.

Scheme for determining an IP address by domain name

This diagram briefly explains what happens when you want to visit a particular site.

1. 1 Your computer contacts your ISP's DNS servers ( arrow 1). The provider's DNS servers look for the IP address in their cache (an intermediate buffer with quick access) and, if they find it, they give you this IP and via IP your computer accesses the server on which the site is hosted ( arrow 7).
2. 2 If the “domain-IP address” pair is not in the cache, then the provider’s DNS server makes recursive queries to the root DNS servers ( arrow 2), of which there are only a few around the world. Changes in domain settings on root servers are not updated instantly, but every few hours. For example, changes in root DNS servers RU zones are updated only 4 times a day. Root servers return the addresses of the domain's DNS servers ( arrow 3) on which the DNS zone of the domain is stored.
3. 3 Having received the addresses of DNS servers, the provider makes a request to one of them ( arrow 4), receives the required IP address in response ( arrow 5), stores it in the cache (so that you don’t have to contact the root DNS server every time) and passes it to your browser ( arrow 6).
4. 4 And only now that the browser has the site’s IP address can it contact the hosting server on which the site is located ( arrow 7), and can display it on your computer screen ( arrow 8).

So:

• Information on root servers is updated only a few times a day.
• Internet providers, as a rule, update the DNS server cache no more than once a day (some providers update the cache even less frequently, but usually no more than 72 hours), so if after registering or transferring a domain (changing DNS servers), The site didn't work right away, don't worry - just wait a while.
• To check if DNS has been updated, use .

The above structure DNS work greatly simplified; for details, you can refer to the reference literature on the Internet.

DNS server is extremely useful opportunity secure own computer from malicious sites. The process seems difficult for beginners, but in reality everything is much simpler, and the procedure for installing a DNS server will not take much time.

DNS is an acronym derived from Domain Name System. WITH English language this translates into Russian as “Domain Name System” changing them into IP addresses. And the DNS server stores the corresponding addresses in the database.

The work is carried out in this way: the browser, going to the site, contacts the DNS server to find out the desired address. The Server identifies the site, sends a request to it, and sends the received response back to the user.

How to find out if the DNS server is enabled on your computer

The current DNS server settings are determined as follows:

1. “Control Panel” -> “Network and Internet” -> “View network status and tasks.” Select your network connection, go to the “General” panel, then go to properties.
2. Go to the properties of “Internet Protocol Version 4 (TCP/IPv4)”.
3. Open the "General" tab. If the option to use the following DNS server addresses is activated, it means it is in working mode.

Repeat the previous steps, activate “Use DNS server”. After this, you will need to specify a primary DNS server, and then a secondary one.

How to configure/change DNS

When changing or additional settings you don't need to do much. You must use the window that was opened earlier and go to the “Advanced” item. Here, detailed adjustment of access to DNS servers is carried out. In Windows 7, you can configure all this yourself. Therefore, the question of how to change the DNS server yourself will not cause problems.

DNS suffixes are also available for management. The average user does not need them. This setting, which helps to conveniently share resources, was created for providers.

On a wi-fi router

When using a router, you must set its IP address in the DNS options. To perform these manipulations, you will need DNS relay and DHCP server enabled.

The router interface is designed for verification and subsequent detailed settings. First you need to check the DNS in the WAN port. DNS relay is activated in the LAN port settings.

On the computer

Setting up a DNS server in Windows 10 is similar to the same situation in earlier versions OS. First you need to select the “Internet Protocol Version 4 (TCP/IPv4)” properties. Go to additional options and configure the list of servers.

Setting up a DNS server on a computer and on a laptop is the same.

On a tablet

Depending on the installed operating system, the actions differ somewhat, but they all have the following points in common:

• Open the “Wi-Fi” menu located in “Settings”.
• Go to the properties of the current Internet connection.
• Click “Change network”, then “Show additional parameters”.
• Scroll to the DNS servers item, then register them.

On a smartphone

Since now there is not much difference between operating systems I don’t have a phone or tablet; to set up the necessary DNS servers, you just need to know the instructions described above.

Possible errors and how to fix them

Problems with the Internet occur when incorrect settings DNS servers, including when they unexpectedly fail.

What to do if the server is not responding or is not detected

Most often, this problem occurs when the server is disconnected or the settings are lost. To do this, open the “Control Panel”, go to “System and Security”, then “Administration”. Click on “Services”, find “DNS Client” and double-click on it. The status bar indicates the command “Running”. Otherwise, you need to select automatic startup type from the drop-down list above.

If the service is running but the error still appears, there are server problems. First, it is better to change the DNS server addresses according to the above instructions. However, it is still possible to reinstall the drivers network card, check your Internet connection and ask your provider about possible technical problems.

Doesn't resolve names correctly

If this error occurs, you need to check the correctness of your DNS server settings. It’s better to simply change the DNS server address to get rid of the problem.

Problems are also possible on the operator’s servers, and the problem is solved in the same way - by changing the DNS.

For the inexperienced user, there is a list of high-quality and free servers:

Addresses: 8.8.8.8; 8.8.4.4

Like everyone else Google services, performs its tasks efficiently, but has a known disadvantage - it collects and stores user statistics. Despite this, the server does not have any access to personal data, so there is no need to worry about security.

If you want to learn more about server work, there is official documentation on the information site.

OpenDNS

Addresses: 208.67.222.222; 208.67.220.220

A popular server due to the presence of a wide range of filters and protection against theft of personal data. Basic functions are free, but it is possible to purchase premium access, which allows you to create a “locked network environment” and increase connection speed.

DNS.WATCH

Addresses: 84.200.69.80; 84.200.70.40

Does not require registration to use, provides a more serious level. The only negative is the low speed.

Norton ConnectSafe

Addresses: 199.85.126.10; 199.85.127.10

It also does not “ask” for pre-registration and securely stores user data. Created by the developers Norton antivirus, without requiring additional advertising.

Level3 DNS

Addresses: 4.2.2.1; 4.2.2.2

Suitable not only for personal use, but also for corporate purposes. Fully free resource, ranks third in global popularity.

Comodo Secure DNS

Addresses: 8.26.56.26; 8.20.247.20

The basic version is free, but some cash it is possible to purchase large quantities useful services. Both paid and free options provides reliable protection data.

OpenNIC DNS

Addresses: you should go to the project website, it will select the best ones depending on the user’s location.

Due to its huge coverage, it allows you to conveniently explore the Internet anywhere in the world.

DHCP server: what is it and what are its features

Most suitable for meshes with large quantity computers due to the transfer of their network settings all connected devices.

Such a server allows the administrator to specify a range of server hosts and avoid wasting a lot of time on detailed optimization.

It only works with IP address settings and the addresses themselves.

Conclusion

The primary task of DNS servers is to transfer an IP address. Servers from other companies, some of which are described above, can speed up and greatly facilitate Internet surfing. However, it does not require painstaking setup, and many errors can be resolved by using another server.

480 auto

If you ask the average Internet user what a website is, most likely he will name, for example, yandex.ru, mail.ru, google.com, facebook.com, ...

In a practical sense, this is quite enough: I found an interesting site, told my friends its domain name (or more simply, “address”).

However, the domain name is not a real address. Well, this is about the same as sending a letter with the inscription on the envelope: “city of Yekaterinburg, to Peter Ivanov.” The point here is not even that there may be several Petrov Ivanovs in Yekaterinburg (let’s imagine that there is only one person with that name). The problem is that the addressee can move, at least, around the city, and handing him a letter will be extremely problematic.

But letters are delivered and received! - Yes, sure. Because they send by postal addresses. For example, “city of Leningrad, 3rd Stroiteley Street, building 25, apartment 12.”

A postal address on the Internet is an IP address consisting of four numbers from 0 to 255, for example, 74.125.131.100. This is one of the IP addresses of the google.com website. If in address bar enter these numbers into your browser, you will find yourself on the google.com portal, more precisely, on google.ru, where you will be automatically redirected.

Why “one of the addresses” and what types of IP addresses there are, we will leave aside for now.

On the Internet, the IP address determines which computer the data should be delivered to.

Does the IP address remind you of anything? - It reminds me of a long number mobile phone.

Phone book

Unfortunately, remembering long phone numbers is not easy. We include them in our notebooks(“contacts”, in mobile phone) and add clear names to them, for example,

Peter Ivanov, +7-343-123-45-67.

In the future we will not need to remember telephone number Peter, it’s enough that this number is recorded in our phone book. When we need to call Peter, we will find him in our contacts list without even looking at his number.

On the Internet, the role of a phone book plays domain name system(DNS, Domain Name System). It stores the relationship between the relatively easy-to-remember site name and its hard-to-remember numeric address.

True, there is one significant difference between this “Internet book” and a telephone one. “It is not led by every acquaintance of Pyotr Ivanov individually, but by himself.

In a private phone book you can write: “Petya”, “Peter”, “Petrusha”, “Petrukha”, “Petrunya”, “beloved”, ..., and in the “Internet telephone book” entries are kept by the site owners themselves, for example:

If someone wants to visit the website of Peter Ivanov, in the address bar of the browser he will type: pyotr-ivanov.ru, and the domain name system will tell the browser (more precisely, the computer on which the browser is running) the corresponding IP address, in our example: 123.123 .123.123. The computer located at this address will process the browser request and send it data to display the requested website page.

Now do you understand how domain names are used? “However, it has not yet been said where records of connections between domain names of sites and the IP addresses of the computers on which these sites are located are stored.

DNS server

He is the one who serves phone book. It stores information about which IP address a particular domain name corresponds to. There are a lot of DNS servers on the Internet. They have a dual role:

• the main one is “Internet phone book”;
• additional (but also important) is caching records of other DNS servers.

First, a few words about caching. Finding out the connection between a site's name and its IP address is required every time you access that website. If the site you want to visit is far away, multiple queries to a distant primary DNS server can be time-consuming and slow down web pages. To avoid delays, the DNS server closest to your computer (usually located at your Internet service provider) stores information about previously requested IP addresses, and when you access the same site again, it will report its address very quickly, since it will store it in your cache.

But in order to cache something, you need to have a source of what is being cached. This source is the primary DNS servers, which store the initial relationships between domains and their IP addresses.

To register a domain name, you just need to come up with one. But in order for it to start working, you must tell the registrar the domain name of the DNS server, which will store detailed data about the domain you are registering. These data will be discussed a little later.

Typically, two DNS servers are used: primary and secondary. But there may be more. Larger number DNS servers increase the reliability of access to your domain: if one is unavailable, another will respond.

In the real world, two are enough.

Many domain name registrars and Internet providers offer the use of their DNS servers as a paid service.