>> As I understand it, only very recently changed domain addresses would
>> be affected by a temporary failure of the root servers.
> If *all* the root name servers had been taken out, there would have
> been a huge impact. Any domain that wasn't cached by your server
> wouldn't have resolved. But taking them all down isn't an easy task.
>formatting link
And some of us keep our own little IP cache, just in case. Cox's name servers frequently go down so I've had to resort to that.