What is a domain name server (DNS)?

A Domain Name Server (DNS) is a crucial component of the internet infrastructure that translates human-readable domain names (like "example.com") into numerical IP addresses (like "192.0.2.1") that computers use to identify each other on a network.

Here's how DNS works in a nutshell:

Domain Name Resolution Request: When you type a domain name into your web browser's address bar or click on a link, your device sends a request
to a DNS resolver, asking for the IP address associated with that domain name.

DNS Resolution Process: The DNS resolver, which could be your Internet Service Provider's (ISP) DNS server or a public DNS resolver like Google DNS or Cloudflare DNS, starts the resolution process by checking its local cache to see if it already knows the IP address associated with the domain name. If the information is not cached locally, the resolver queries the DNS hierarchy to find the IP address.
DNS Hierarchy: The DNS system is organized hierarchically, with multiple layers of DNS servers. At the top of the hierarchy are the root DNS servers, which store information about the top-level domain names (like .com, .org, .net). Below the root servers are the authoritative DNS servers, which store information about specific domain names, such as example.com.
Recursive DNS Query: If the resolver doesn't have the IP address cached, it sends a recursive query to the root DNS servers, asking them to provide the IP address of the authoritative DNS server for the top-level domain (TLD) of the requested domain name (e.g., .com).
Iterative DNS Query: The root DNS servers respond with the IP address of the TLD's authoritative DNS servers. The resolver then sends an iterative query to the TLD's authoritative DNS servers, asking them to provide the IP address of the authoritative DNS servers for the second-level domain (e.g., example.com).
Authoritative DNS Server Response: The TLD's authoritative DNS servers respond with the IP address of the authoritative DNS servers for the requested domain name (e.g., example.com). The resolver then sends a query to the authoritative DNS servers for the requested domain name, asking them to provide the IP address associated with the domain name.
IP Address Response: Finally, the authoritative DNS servers respond with the IP address associated with the requested domain name. The resolver caches this information locally for future use and sends the IP address back to the requesting device.
Accessing the Website: With the IP address in hand, your device can now connect to the web server associated with the domain name and retrieve the requested web page or other content.
In summary, a Domain Name Server (DNS) is a critical part of the internet's infrastructure that translates domain names into IP addresses, enabling users to access websites and other online resources using human-readable names.