What is DNS? (“The Phonebook of Internet”) – Cheatsheet

DNS, or the Domain Name System, resolves human readable domain names (for example, http://www.hacksheets.in) to machine readable IP addresses (for example, 192.0.1.45).

DNS Resolution Steps

1. A user types ‘www.hacksheets.in’ into a web browser and the system sends the query to a DNS resolver.
2. This resolver then sends the query to the DNS root nameserver (.).
3. The root server then responds to the resolver with the address of a Top-Level Domain (TLD) DNS server (.in)
4. The resolver then makes a request to the .in TLD.
5. The TLD server then responds with the IP address of the domain’s nameserver, http://www.hacksheets.in.
6. The resolver sends a query to the domain’s nameserver.
7. The IP address for http://www.hacksheets.in is then returned to the resolver
8. The DNS resolver then responds to the web browser with the IP address of the domain.
9. The browser makes an HTTP request to the IP address.
10. The server at that IP returns the webpage to be rendered in the browser.