The DNS cache is database run by a computer's operating system. It contains records of all recently accessed Internet domains. When the location of the page changes before the entry in your DNS cache is updated this can cause problems accessing the page.
To clear this use the following:
Windows XP, 2000, Vista, 7, 8
A) Open the Start Menu
B) In the search bar (or via the programme menu) find Command Prompt and right click on it. Select "Run as Administrator"
C) In the command prompt box, type in:
ipconfig /flushdns
press Return or Enter.
MAC
Use the following: http://support.apple.com/kb/HT5343
