If you’re stuck with a host that has no working DNS cache, and if you forgot OpenDNS IP addresses, you can always use 4.2.2.1 and 4.2.2.2
Those IP addresses are Level 3’s public DNS caches.
They are easy to remember and they won’t answer on non-existent zones like OpenDNS does. And they are very fast. And Level 3 keeps their servers up-to-date.
But they are standard caches. For real use, if you aren’t planning to run your own cache, nothing can beat the features of OpenDNS.