Definition of DNS Servers

How do you know where a certain friend yours? Very simple: he knows the name of the street on which the building he lives is located and the number of that building. And, inside it, the floor and the door.

Similarly, computers connected to Internet They are also assigned an address, in this case numeric. It is what is called an IP address, and it usually has the Format of four groups of numbers with a maximum value of 255 each, separated by dots.

For example, an IP address could be 172.65.134.3.

DNS servers are a mnemonic system to avoid having to remember numbers

Let's imagine that all computers connected to the Internet have to be accessed by these numbers. So instead of connecting to www.definicionabc.com we should to write 208.43.211.172 (try entering these numbers in the address bar of your browser and be surprised). Which of the two ways is easier for you to remember? the one from www... truth?

As those of us who must work with computers we are, after all, human beings, and we rely more on being able to remember words than not sequences of numbers, from the beginning of Internet and the networks that preceded it, there have been systems that have made it possible to transfer a name to its numerical equivalent, which is what computers use to communicate with each other. they.

To understand what DNS does, we will say that it is like an address book where we ask for the name of a friend, and she returns her phone number.

A system distributed throughout the Internet and hierarchical

When from the web browser of our computer We launch a request to access a specific website, the first thing it does is check if we have already accessed it before, since if it were, we would still have your IP address in the HDD, since it is stored in a file that serves as memory cache for these purposes.

In the case of not finding the numerical translation of the address sought, the request (resolution) is passed to the DNS servers (consisting of computers dedicated only to this task) from our Internet access provider, that is, the company that provides us with access to the network of networks.

If the translation is not found on our provider's servers, they are in turn connected to other DNS servers, which all operate in the form of a hierarchical tree structure, so that our request travels to the velocity of the light until the adequate answer is found, which is forwarded to us.

It is, as if in a room full of people, we asked a question to the one next to us and, if he does not know the answer, did it to those around him, until he found someone who knew the answer correct. So that answer would go the other way until it reached us.

There are three types of DNS servers according to their function:

• primary or master: are the main
• secondary or slave: they depend on the previous ones, from which they obtain a part of their data. Its mission is to provide geographically close data
• local or cache: the most frequent, and are of the type available to most access providers that are not part of large communications companies. When they make a request to a primary or secondary DNS, they save the result to offer it again at other times in the future

A select group of DNS servers make up the spine from Internet

There are 13 special DNS servers that make up an index of indexes, so that any name resolution can be successfully redirected to the proper primary. These 13 servers are called root servers.

It is said that whoever wants to paralyze the Internet, must bring down these thirteen servers. Some have tried, no one has succeeded. The challenge is not easy.

Photos: iStock - Barış Muratoğlu / matdesign24

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