The Athena code supports, in hesiod.conf (everything
case-insensitive, spaces okay):

	classes=IN
	classes=HS
	classes=IN,HS
	classes=HS,IN

with fallback behavior when there's a comma-separated list (the
default on Athena is in,hs).  Class IN is definitely preferred, since
class HS requires that the world create an entirely new DNS hierarchy
and teach everybody's named about its root name servers.  It's
unfortunate that class HS ever came up in the first place; the people
who made that decision did not apparently understand DNS
administration very well (see
http://www.mit.edu:8008/menelaus/hesiod/11).  But that was over a
decade ago and this is now.

So, we can do one of:

	* Leave things alone and let people in your situation lose
	  (unless you can teach your name servers to answer class IN
	  as well as HS).

	* Hack in support for at least "classes=IN" and "classes=HS"
	  in the current sources.

	* Update to the current Athena Hesiod code.  (Presumably means
	  KNFifying it and making any changes Luke made to the ancient
	  code he took.)

I don't have a great setup for testing libc changes or I'd offer to do
the last option (and possibly even not drop the ball).  If anyone else
wants to, the current distribution is at
athena-dist.mit.edu:pub/ATHENA/hesiod and all the stuff you'd want to
borrow is in hesiod.c.