domännamnssystemets

The Domain Name System, or DNS, is a hierarchical and decentralized naming system for computers, services, or any resource connected to the Internet or a private network. It translates human-readable domain names, like example.com, into machine-readable IP addresses, such as 192.0.2.1, which computers use to identify each other. Without DNS, users would have to remember numerical IP addresses for every website and service they want to access.

The DNS hierarchy is structured like an inverted tree. The top of the hierarchy is the root, followed by top-level domains (TLDs) such as .com, .org, and .net, and then country-code TLDs like .us or .uk. Below these are second-level domains, which are the actual names registered by individuals and organizations, such as "example" in "example.com". Each level is managed by a different set of name servers.

When a user types a domain name into a web browser, their computer sends a query to a DNS resolver. The resolver then recursively queries a series of DNS servers, starting from the root servers, to find the authoritative name server for the requested domain. This authoritative server holds the IP address associated with the domain name, which is then returned to the resolver and subsequently to the user's computer, allowing the browser to connect to the correct server. DNS is a critical component of the internet's infrastructure, enabling seamless navigation and communication.