The following is a simple implementation of how a DNS Resolver actually works, and how it maps ip-address to incoming domain-name requests and reponds it back.

We use a recursive approach by starting at a rootname server ( queried to by the DNS resolvers), and go down till we find the match recursively( i.e. IP address) and return it.

There are a total of 13 rootnameservers in the world, and multiple servers anycast these rootnameserver ip's.