RE: How common is lack of DNS server diversity?

> More interestingly, how many root servers allow recursive lookup?

a quick looping probe shows that none of them do, nor the gTLD servers
(phew!) although L.ROOT-SERVERS.NET and H.GTLD-SERVERS.NET
are unreachable
from my view. Preparing an accurate list of all TLD servers
glued in the
root zone will take a little longer.

I was taking about root servers at ALL levels, not just the root.

I believe the phrasing Roeland may be looking for is "how many *zone*
servers (ie: authoritative servers, not customer resolvers) allow
recursive lookups", no, Roeland?

Cheers,
-- jra