[Naspino]

There are thirteen critical servers I believe. The most recent attack (largest in history) took down eight and another 1 partially. There was little or no visible impact on the internet; however they said if the attack had lasted longer than an hour it would have started to slow down users. I believe some are even located outside of the country and their location is a closely guarded secret.

[JSpears]

The servers you refer to are the "root" DNS servers....

Their domains are the "top" level domain which is designated
as the "." domain...