Every time you type a URL into your browser, a complex chain of lookups happens behind the scenes. DNS — the Domain Name System — is one of the most critical pieces of internet infrastructure, yet most developers only think about it when something breaks.
Let us walk through what actually happens when you visit a website, from your local resolver cache all the way up to the authoritative nameservers.
The Lookup Chain
Your browser checks its cache first. Then the operating system cache. Then your configured DNS resolver — often your ISP or a public resolver like 1.1.1.1 or 8.8.8.8. If none of them have the answer, the resolver walks the DNS hierarchy: root servers, TLD servers, and finally the authoritative server for the domain.
Understanding this chain helps you debug propagation delays, TTL issues, and the occasional mystery of “it works on my machine but not in production.”