How to flush your DNS

Most computers that are connected to the internet automatically cache the hostname of the websites you have visited to make reloading the pages faster than if there was no cache. If the IP address of a website changes before your cache updates, you may not be able to load the webpage.
If you have recently Changed your Name Servers or moved your website from one host to another and are unable to see your site and you’re getting that “Default Webpage”  then whats likely happening is your name servers haven’t finished Propagating which can in some cases take up to 72 hours. Below are a few easy steps to take to Flush your DNS

Method One: Windows
1.    Open the command prompt. The command to flush DNS needs to be entered in the command prompt. Accessing the command prompt is slightly different depending on which version of Windows you are running:
Windows 8 – Press the Windows key + X and select “Command Prompt (Administrator)”.
Windows 7/Vista – Click the Start menu and enter “cmd” into the Search field. Right click on Command Prompt and select “Run As Administrator”.
Windows XP – Click on the Start menu and then click Run. Enter “cmd” into the Run field and press Enter.
2.    Use the DNS flush command. Type ipconfig /flushdns and press Enter. A message will appear stating “Windows IP configuration successfully flushed the DNS Resolver Cache”.
3.    Exit the command prompt. Type exit and press Enter. This will close the command prompt.[1]
Method Two: Mac OS X
1.    Open the Terminal. You can find the Terminal application in the Utilities folder in your Applications folder.
2.    Enter the DNS flush command. The command varies depending on which version of Mac OS X you are running.
Mountain Lion or Lion – sudo killall -HUP mDNSResponder
Snow Leopard – dscacheutil -flushcache
Leopard and older – lookupd -flushcache
3.    Enter the password. You will most likely be asked for the administrator password before you can proceed with the DNS flush.[2]