What is a DNS Cache?
A DNS cache is a temporary database, maintained by a computer's operating system (Windows etc), that contains records of recent visits and attempted visits to web sites and domains.
The internet uses Domain Name System or DNS to index public Web sites and IP addresses. Every time a user visits a web site the user's Browser (Chrome, Firefox, Safari, etc) initiates a request to visit that web site, but this request cannot be completed until the Web site name is converted into an IP address.
That conversion process is the job of DNS, and it takes time to complete. A DNS cache attempts to speed up the process by handling the name resolution before the request is sent out.
Before a browser issues its requests to the outside network, the computer operating system intercepts each one and looks up the domain name in the DNS cache database. The database, stored in the computer's temporary memory, contains a list of all recently accessed domain names.
When you point a domain name to a different server with a new ip address you computers temporary memory can often provide the wrong ip address giving you a web site error.
If the DNS information of a website has changed, then the information stored in a computer’s DNS cache will have to be updated as well, or else the user will encounter problems when trying to access the website. This can be achieved by flushing or refreshing the DNS cache. Through this, the old and outdated information of a web address will be removed from the computer’s DNS cache, and the updated DNS information will be stored in its place.
How You Can Flush the DNS on your PC (Apple Users will have a different method)
1) Open your computer command prompt: Start > All Programs > Accessories
2) Right Click and select Command Prompt and select Run as Administrator (if you don't click run as administrator this process won't work correctly)
3) Type the following command prompt: ipconfig /flushdns
4) If it worked properly you will find a message that says Windows IP Configuration Successfully flushed teh DNS Resolver Cache