Since we support IPv6 transport DNS queries in libc resolver,
	I think we should support EDNS0 to take advantage of larger minimum
	MTU.  Does it sound right to bring it in before 1.5, switchable by
	"options edns0" on /etc/resolv.conf? (since BIND4/8 chokes with
	EDNS0, we should make it off by default - BIND9 works just fine)

	We have some code in
	http://www.kame.net/dev/cvsweb.cgi/kame/kame/kame/libinet6/resolv/
	(check #ifdef RES_USE_EDNS0 in res_*.c)

itojun