http://www.washingtonpost.com/wp-dyn/articles/A828-2002Oct22.html

only 4 survived!

 

Or, put another way, only 60% were successfully targetted. Seems to me that the redundancy worked perfectly.

 

By 'root servers' I presume they mean the root DNS servers. Not such a problem until your local DNS server's cache expires, or you need to look up an address it hasn't got.

In reality, if all the root DNS servers fell over the Internet would take a while to grind to a halt, because it wouldn't affect any traffic that was in progress. Unlike when a small ISP a few years back started advertising most of the Internet as being available via itself in its BGP advertisements