- When user enters a web address → Browser sends a message(recursive DNS query) to the network to find out which IP corresponding to it recursive resolver server – maintained by ISP
- If IP address found , it send IP to browser, if it’s not available SEND request one by one server DNS Root Name servers,
- If IP Address not found in Root Name server, Request send to Top Level Domain (TLD) name servers
if it found returns to browsers, other else - Sent request to authoritative name servers
- after all 4 server , IP not found, then it revert error message to Browser, like .. shows site can’t be reached