DNS (Domain Name System) is a hierarchical, decentralized system for managing domain names and mapping them to IP addresses. DNS name resolution is the process of converting a domain name (such as www.example.com) into the corresponding IP address (such as 192.0.2.1).
Here's a high-level overview of how DNS name resolution works:
A client device (such as a computer or smartphone) sends a request to a local DNS resolver, asking to resolve a domain name.
The local DNS resolver checks its cache to see if it has a recent copy of the DNS record for the domain name in question. If it does, it returns the IP address to the client device.
If the local DNS resolver does not have a recent copy of the DNS record, it sends a request to a root nameserver. The root nameserver responds with the IP addresses of the top-level domain (TLD) nameservers (such as .com or .net).
The local DNS resolver sends a request to the TLD nameserver, asking for the IP address of the domain name in question. The TLD nameserver responds with the IP address of the authoritative nameserver for the domain.
The local DNS resolver sends a request to the authoritative nameserver, asking for the IP address of the domain name. The authoritative nameserver responds with the IP address for the domain name.
The local DNS resolver stores the IP address in its cache and returns it to the client device.
This process happens quickly, typically in a matter of milliseconds, so that the client device can access the requested website or resource.
DNS name resolution is an essential part of how the internet works, as it allows users to access websites and other resources using easily memorable domain names rather than having to remember and enter the IP addresses of those resources directly.