How does DNS work?:

• End user enters the desired domain name (www.yourdomain.com) into the browser.

• The browser then contacts the ISP to get the IP address for the domain name.

• The ISP then attempts to answer by itself by using the 'cached' information.

• If the answer is found then it is returned to the browser. Since the ISP isn't in control of the domain name it is merely acting as a relay. The answer is marked as a non-authoritative response.

• If the answer is not found or it is too old (past the TTL - time to live) then the ISP contacts the nameserver for the domain directly for the answer.

• If the nameservers are not known, then the ISP looks for the information at the 'root servers' or the 'registry servers'
  
  Note: 'whois' information is never used for DNS, and is often misleading or inaccurate.