The DNS root is pretty well distributed. There's 13 different IPs run by several different organizations, and AFAIK they're all running anycast these days. And anyway, the root zone is tiny, changes infrequently and could really be AXFRed a couple times a month and you wouldn't miss much.
The larger tlds aren't quite as diversely hosted and certainly aren't amenable to long term caching, but it should take a major f up to break those too.
Some of the minor tlds, even the more popular ones do screw up from time to time though.
The larger tlds aren't quite as diversely hosted and certainly aren't amenable to long term caching, but it should take a major f up to break those too.
Some of the minor tlds, even the more popular ones do screw up from time to time though.