How does DNS operate?

Basic DNS Name to IP RESOLUTION:

 

When we look for a domain name, the query will first search the host file of the client machine, then the dns cache. If the IP is not getting resolved, the query will be forwarded to the dns server ip address of the machine which we have got from dhcp server( or manually added). if the dns entry is located, it will update the dns cache and we can have the website or something.

                           if not it will look for a dns forwarder first. if the forwarder exist, the query moves to the forwarder. if query is not resolved, it will come back to the dns server and looks for root server list. from any of  the root server the ip get resolved. Whenever the we get the ip, it is updated to DNS cache file. Thats it.

domain name server it Chang the name to in ip address like fully qualified domain  

DNS translates fully qualified domain names to IP addresses. In layman's term if you type www.cnn.com in your browser, your system connects to DNS server on port 53 to resolve it to an IP address and then it connects to CNN server to pull website data for you to display.