What is DNS and what is it for?

Full information about Domain Name System (DNS) you can read on Wikipedia. In simple terms, DNS is a system that ensures the operation of domain names we are used to. The main area of application of this system is the conversion of a host name to an IP address and the provision of mail routing information.
 

DNS operation principle:

• When a user enters the domain name of the site in the browser, his device (PC, phone, tablet) sends a request to the ISP's DNS server to get the IP address where the domain is located
• If information about the requested site is not in the cache on the provider's DNS servers, a request is sent to the root DNS servers.
• The root DNS server searches in its database for information about the name servers of the hosting provider on which this site is present and reports them to the provider's caching DNS server
• After the ISP's caching DNS server obtains information about the name servers of the hosting provider, it polls any of them and, in the case of obtaining an IP address, places it in a cache. Caching is used to reduce both the load on Internet channels and to speed up the receipt of the query result
• After that, the provider's DNS server sends the IP address to the user's browser that made the site request
• And after that, the browser, having received the IP address of the requested site, sends a request to the server (the same IP address)

Updating the information received from the server of the provider’s name is not instantaneous, but after a certain time, depending on the settings of the caching server of the Internet provider, name server of the hosting provider and root DNS server.