To better illustrate how website urlworks, let’s imagine you are sitting at a computer in your study at home. You’re connected to the Internet by a cable connection and you are surfing the web looking for widgets. You have no idea where to find widgets, so you open your web browser and type in http://www.google.com.

This is when recursive DNS kicks in. Your web browser looks to see if it knows where to find the machine “www.google.com”. If it doesn’t have this info stored in its own cache, it will ask your operating system (OS) if it knows where to find this host. If your OS doesn’t have this in its cache, your OS will perform a DNS query to find that info. That query will go to the DNS servers provided by your ISP and these servers are configured to provide recursive DNS.

To simplify things, the ISPs nameserver will send a query to the “root” name servers to find out who is responsible for the .COM domain (i.e. which name servers are authoritative for the .COM domain). Once it has this info, it will send a DNS query to those nameservers asking them who is responsible for the google.com domain and then a final query to those name servers asking for the address of www.google.com.