In order to resolve a domain name, it must be registered and pointed to at least two name servers which will host the DNS zone file for the specific domain. These servers are authoritative so when someone on the Internet “asks” for the IP address of the specific domain, the request will first go to the root name servers for the requested TLD (top level domain, for example: .com, .net, .org, etc.). They will reply with the authoritative name servers for the requested domain and the request will go to the server hosting the file with the DNS records where the IP will be resolved from.

Oh, there’s more… Read the complete article at Siteground including detailed instructions on how to clear the DNS cache to help your site resolve faster.