nevypadlo DNS Vám, ale jim. Proto nejedou jenom oni.
$ dig facebook.com +trace
...
facebook.com. 172800 IN NS a.ns.facebook.com.
facebook.com. 172800 IN NS b.ns.facebook.com.
facebook.com. 172800 IN NS c.ns.facebook.com.
facebook.com. 172800 IN NS d.ns.facebook.com.
...
couldn't get address for 'a.ns.facebook.com': failure