ARIN?

Jeff Mcadams wrote:

Mostly because reverse lookups for blocks longer than /24's is still a
hassle...it can be done, but is still a hassle...oh...and some things
still break with CNAME -> PTR (a recent discussion on BUGTRAQ
illuminates one)

I delegate the reverse lookups when requested, though few do so. I have
a /28 at home and I have done the delegation. And I did it without using
the CNAME trick. I find it less confusing, although more stuff to type.
At least things don't break.