What is a DNS Server?

A DNS server (Domain Name System), is a computer or a group of them connected to internet nodes, which have a database, our navigators consult regularly.
They work as a book of Internet addresses, resolve (translate) or convert domain names into IP addresses.

Not only browsers, but also mail programs when sending a message, mobile applications to operate, devices to connect to, and anything else that needs to find the address of a domain come to this server. They also have other functions.

Functions of DNS servers

Resolution of names

This term consists of returning the IP address that corresponds to a domain. Internet sites and services get identified by their numeric IP addresses, almost impossible to memorize by humans. For that reason, domain names were created. When requesting the browser for an address, it accesses the nearest DNS, which returns the IP corresponding to the requested site.

For example, when clicking on the link https://norfipc.com, we must wait  for the request to travel to the default DNS of the connection and return the result 31.22.7.120. Then can the browser request the indicated page from this site. Of course, after that, this relationship is saved in the cache for a while, to speed up subsequent queries.

Inverse address resolution

It is the reverse mechanism to the previous, from an IP address get the corresponding hostname.

Resolution of mail servers

Given a domain name (for example, gmail.com), obtain the server through which the e-mail delivery should be made.

The DNS Servers store a series of data for each domain, which is known as “DNS Record”.
The registers A, AAAA, CNAME, NS, MX, among others contain the IP addresses, host names, canonical names, associated email addresses, etc.

Main Internet DNS servers

There are thousands of DNS servers located on different internet nodes. Some get managed by ISPs (Internet supplying companies), others by large companies and there are even personal DNS. Some of them have a small database and queries about sites that got not included, are “passed on” to others that are hierarchically superior.

There are 13 DNS servers on the Internet that are known as the root servers, they store the information of the servers for each of the highest level areas and constitute the center of the network. They get identified with the first seven letters of the alphabet, several of them are physically divided and geographically dispersed, a technique known as “anycast,” with the purpose of increasing performance and safety.

Delay in name resolution

When trying to access with our browser to a website that we had never been before, also little known and that is on a remote server, the request gets made to the default DNS server of our connection, which 80% of the time It’s from a telephone company.

This DNS is generally slow and with little information. The request will send it to another DNS of higher rank and so on until it succeeds.  If the application gets delayed for a certain amount of time, the browser will consider it an error and close the connection.

Errors and censorship in DNS

In addition to the slowness caused by poor quality DNS and poor performance, other factors conspire against the quality of navigation. One of them is errors in the resolution of names when it seems that the sites or internet services do not work and it does not. Another is the use of DNS to censor or block websites, an extended method in some countries.

Alternate internet DNS servers

Due to the difficulties explained above, the use of alternate servers on the Internet has become popular. They are independent services to providers, which generally offer free services, which often include the filtering of inappropriate or dangerous content, such as malware sites or adult-only content. The main ones offer much smaller response times than telephone companies, which considerably increases the quality and performance of navigation. The best known of these is the Google DNS Public Server, whose IP address is: 8.8.8.8.

How to know the DNS servers of our connection

1. Open Start, type CMD and press the Enter key to open the CMD Console or Command Prompt.

1. In the black window write the command NSLOOKUP and press Enter again. The application will return the hostname and the IP address of the established DNS, as you can see in the following image.