First what is DNS (Domain Name Servers)

If you spend any time on the Internet sending e-mail or browsing the Web, then you use domain name servers (DNS) without even realizing it. Domain name servers, or DNS, are an incredibly important but completely hidden part of the Internet. The DNS system forms one of the largest and most active distributed databases in the world. Without DNS, the Internet would shut down very quickly.

What is a Cache?
Basically (in easy to understand terms) a cache is your computers way of making things faster for you. Basically when you visit a website it takes a snap shot of the visit so that if you go back to it then it will show you the snapshot to save time vs actually taking you to the site. Generally your computer will verify the the address with the server (The DNS) to make sure it is correct.

So why do people dump their cache's?