[dns-operations] DNS trust dependencies for ICANN TLDs

[Matthew Dempsky]

I've assembled a collection of graphs of zone and name server trust
dependencies for each ICANN TLD at

    http://shinobi.dempsky.org/~matthew/dnstrust/graphs/

I've heard claims from some TLD operators that extra dependencies are
actually intentional, but I haven't yet heard any arguments to justify
that claim.  Can anyone here offer arguments in favor of making TLDs
dependent name servers other than the ones authoritative for that TLD?

I plan to automate regenerating the graphs on a regular basis and to
start contacting TLD operators to point out particularly egregious
cases (e.g., .cn is dependent upon 247 extra name servers, many US
based, because of a single NS record), but I thought I would first
raise the matter here in case anyone had useful feedback.

Thanks.