Ever been working on a test site for a while and then went to change the DNS values only to find that your Mac is holding onto the placeholder or test environment’s numbers?  Well, here’s the solution:  To flush your dns cache on your local machine, open Terminal and paste this command: dscacheutil -flushcache and then hit enter.

If you’re unlucky enough to be on a PC, open your command prompt (search for cmd and it’ll show up) and paste: ipconfig /flushdns and hit enter.