How to Clear DNS Cache in MacOS Sierra

1. Open the Terminal application, found in the Utilities folder within Applications
2. Enter the following command syntax exactly (use copy and paste if in doubt about syntax accuracy):
   sudo killall -HUP mDNSResponder;say DNS cache has been flushed
3. Hit the Return/Enter key and enter the admin password when requested (this is necessary because of sudo privileges)
4. Wait a few moments for the DNS cache to be cleared