The Domain Name System (DNS) is like the internet’s phone book: it translates human-friendly domain names (e.g., example.com) into numerical IP addresses that computers use to communicate. Here’s the basic flow:
-
User request
You type a URL into your browser. The browser asks your configured recursive resolver (often provided by your ISP or a public service like Google DNS). -
Cache check
The resolver looks in its local cache. If it has a fresh record (still within its Time-To-Live or TTL), it returns the IP immediately. -
Root server query
On a cache miss, the resolver asks one of the 13 root servers, “Which nameservers handle the .com TLD?” -
TLD server query
The resolver then contacts a .com TLD server, which responds with the authoritative nameserver for example.com. -
Authoritative query
Finally, the resolver asks that authoritative server for the specific record (A, AAAA, CNAME, MX, etc.). -
Response and caching
The resolver returns the answer to your browser and caches it for the duration defined by the record’s TTL. Your browser connects to the IP, loading the website.
Because of caching at multiple levels, subsequent visits are almost instantaneous—until the TTL expires and the resolver must fetch fresh data again.
