Webservers use IP addresses, for example you have:
- Facebook.com – 22.214.171.124
- YouTube.com – 126.96.36.199
Humans are much better at using Domain Names but Webservers are better at understanding IP addresses.
Here is where DNS comes in, DNS takes out Domain name and converts it into IP addresses.
- Your computer will check it’s local cache both on the computer and the web browser. Also a local configuration file is checked.
- If there are no cache entries found, you computer will send a DNS recursive resolver (QUERY) asking for an IP address.
- DNS recursive resolver(usually managed by the ISP) then checks it’s cache. If it can’t find it in it’s cache then it will send it to the Root Name Server.
- Root Name Server is at the top of the DNS hierarchy. They can refer requests to the TLD (Top Level Domain) server.
- TLD Name Server contains information for domains with a specific extension such as .com .org .net etc.
- Last step of the DNS lookup, is to send it to the Authoritative Name Server which holds DNS record information for the domains they serve.