The Domain Name System (DNS) is the internet's directory that translates human-readable domain names like example.com into the numeric IP addresses that computers use to locate each other.
When you type a domain name, your device asks a DNS resolver for the matching address. The resolver queries a chain of servers, moving from the root to the top-level domain to the domain's authoritative server, until it gets the address, then returns it so your browser can connect.
Resolvers and your device cache DNS answers for a period set by the record's time-to-live, or TTL. Because of caching, repeat lookups for the same name are answered locally and quickly, without querying the whole chain of servers again.
DNS makes the web usable with names instead of numbers, and it lets a site change its underlying address without changing its domain name. If DNS fails, sites become unreachable by name even when the servers behind them are running.
DNS stands for Domain Name System.
A DNS resolver takes a domain name, finds its address by querying DNS servers, and returns the result to your device.
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