Change / Check / Clear DNS from Command Line of Mac OSX

How to Set DNS Servers from the Command Line of OS X with networksetup

Set OpenDNS for the first two DNS servers, and Google DNS as the third fallback:

networksetup -setdnsservers Wi-Fi 208.67.222.222 208.67.220.220 8.8.8.8

Checking DNS Settings with networksetup

This will report back whatever the current DNS settings are, if any:

networksetup -getdnsservers Wi-Fi

Clear the local DNS cache

When URLs are just not resolving the way you want it, to time to clear or flush the dns nameserver local cache:

sudo killall -HUP mDNSResponder

Revert Back and Clear All DNS Servers with networksetup

Remove any existing custom DNS server settings:

sudo networksetup -setdnsservers Wi-Fi empty