The Domain Name System (DNS) is one of the foundations of the Internet, yet most people outside networks probably don't realize that they use it every day to do their jobs, check their email, or spend time on their smartphones.
Simply put, DNS is a directory of domain names that match IP numbers, the numbers in this case being IP addresses, which computers use to communicate with each other.
Each device connected to the Internet has a unique IP address that other devices use to find the device. DNS eliminates the need for humans to memorize IP addresses such as 192.168.1.1 (in IPv4), or more complex alphanumeric IP addresses such as 2400: cb00:2048:1::c629:d7a2 (in IPv6).
The DNS resolution process involves converting the domain name (eg www.example.com) to a suitable IP address of the computer (eg 192.168.1.1), where each device on the Internet is given an IP address, and this address is necessary to find the appropriate Internet device or website - Like using a street address to find a specific house.
When a user wants to load a web page, a translation must occur between what the user types into their web browser (example.com) and the familiar address of the device necessary to locate the example.com web page.
To understand the process behind DNS resolution, it is important to familiarize yourself with the various hardware components that a Domain Name System (DNS protocol) query must pass through. For a web browser, the DNS lookup is done "behind the scenes" and requires no interaction from the user's computer except for the initial request.
A domain name directory that matches name with numbers is not in one place on the Internet, with over 332 million domain names listed at the end of 2017, a single DNS directory would already be very large, the directory is distributed all over the world, and it is stored on domain name servers (commonly referred to as DNS servers) that all communicate with each other on a very regular basis to provide updates and redundancy.
When your computer wants to find the IP address associated with a domain name, it first makes its request to a recursive DNS server, also known as a recursive resolver. Other DNS servers it needs to request to resolve a site's name to its IP address, servers that actually contain the requested information are called official DNS servers.
Each domain can correspond to more than one IP address, in fact some sites have hundreds or more IP addresses that correspond to a single domain name, for example, the server that your computer accesses is likely to be www.google.com is quite different from a server that someone in another country might access by typing the same site name in their browser.
Another reason for the distributed nature of a directory is the amount of time it would take to get a response when you were searching for a site if there was only one directory site, shared among millions, possibly billions of people also searching for information at the same time.
To work around this issue, DNS information is shared between many servers. But information about recently visited sites is also cached locally on client computers.
You probably use google.com several times a day, instead of your computer querying the DNS name server for the IP address of google.com each time, this information is saved on your computer so that it doesn't have to access to the DNS server for name resolution with its IP address.
Additional caching can occur on the routers used to connect clients to the Internet, as well as on the servers of the user's Internet Service Provider (ISP), with so much caching, the number of queries actually reaching the DNS name servers is much less than it appears.
In general, the DNS server you use will be automatically created by your network provider when you connect to the Internet, if you want to know which servers are the primary domain servers - generally a recursive resolver, as described above - there are web utilities that can provide a range of information About the current network connection. Browserleaks.com is a good site, and provides a lot of information, including current DNS servers.
It is important to keep in mind that although your ISP will set a DNS server by default, you are not obligated to use it, some users may have a reason to avoid the ISP's DNS protocol - for example, some ISPs use servers Their DNS is to redirect requests for non-existent addresses to pages with ads.
If you want an alternative, you can instead point your computer to a public DNS server that acts as a recursive resolver. One of the most prominent public DNS servers is Google; Its IP address is 220.127.116.11.
Google's DNS services tend to be fast, and while there are some questions about Google's ulterior motives for offering the free service, they can't get any other information from you that they didn't already get from Chrome. Google has a page with detailed instructions on how to configure your computer or router to connect to Google's DNS protocol.