Let’s meet the cast and see how they communicate with each other!

browser: where’s example.com? (function call)
93.184.216.34!
↓
function: where’s example.com? (DNS query)
93.184.216.34!
↓
resolver: where’s example.com? (DNS query)
93.184.216.34!
↓
authoritative nameservers

browser

Your browser uses DNS to look up IP addresses every time it visits a domain, like example.com.
The browser has a DNS cache.

function

Your operating system provides a function to do DNS lookups. On Linux and Mac it’s getaddrinfo.
Your operating system also might have a DNS cache.

resolver

The function sends requests to a server called a resolver which knows how to find the authoritative nameservers.
The resolver has a DNS cache.

authoritative nameservers

The authoritative nameservers are the servers where the DNS records are actually stored.
They’re wearing crowns because they’re In Charge.