[dns-operations] DNS deluge for x.p.ctrc.cc

[Paul Vixie]

# BTW - personally I've never understood why original designers wanted
# to limit it to only 512 bytes and then go to TCP.

it's due to the minimum maximum reassembly buffer size in the UDP stack as
defined for UDP in the IPv4 era, and constitutes an overspecification.  the
DNS spec should have said "note that the payload should not be larger than
what distant hosts can be required to reassemble, which for IPv4 means 512B,
due to the 568B minimum maximum for IPv4 reassemblers".  this would have let
us "just send 1500" all these years, or fearing silent truncation, at least
it would have let us send 1280 as soon as IPv6 started taking off.