Open DNS is a DNS resolver that caches records beyond their TTL if the upstream DNS server cannot be found. In cases like today’s major outage it can be handy to swap your DNS settings out for this, or it may be worth using as a standard default. Resolution may be a bit slow as it will try to see if the upstream server cannot be found, but it at least can get you back to a working state.
If you know what you’re doing then all you need to do is configure your DNS settings to:
If you need a little more guidance you can go into your System Preferences on Mac, select Network, then Advanced and finally the DNS tab. You should set it up to look as follows: