In message <D1AC4482BED7C04DAC43491E9A9DBEC3901E9E87@BK-EXCHMBX01.blacknight.local>, at 15:08:24 on Sun, 26 Jan 2014, Michele Neylon - Blacknight <michele@blacknight.com> writes
Registry operators - particularly ccTLDs - do this all the time, but I don't see many registrants of domains doing it anymore.
What we have to decide for the purposes of this paper is how often/likely the scenario occurs when the authorities want to block such a domain. If it is no longer happening, raising the possibility only confuses the paper. Perhaps they are using other techniques as well, such as fast flux. Of course, it's possible that there are numerous small/medium/large enterprises (be they of criminal intent or otherwise) with multiply- redundant NS; even if members of the public almost never have the benefit for their personal websites.
And I thought this paper was about domains more than domain registries?
Yes, which is why the paper should positively avoid the inclusion of confusing examples such as domains operated by I* entities. -- Roland Perry