DNS lookup failure by host or dig

[KIMURA Yasuhiro]

I found DNS lookup by host or dig fails if (1) kernel is built without
"options INET6" and (2) DNS server has both v4 and v6 address.

% host -t ns kame.net
kame.net name server orange.kame.net
kame.net name server ns1.itojun.org
% host orange.kame.net
orange.kame.net has address 203.178.141.194
orange.kame.net has address 2001:200:0:8002:203:47ff:fea5:3085
% host orange.kame.net orange.kame.net
Using domain server:
Name: orange.kame.net
Addresses: 2001:200:0:8002:203:47ff:fea5:3085 203.178.141.194

Host not found, try again.
% dig @orange.kame.net orange.kame.net

; <<>> DiG 8.3 <<>> @orange.kame.net orange.kame.net 
; (2 servers found)
;; res options: init recurs defnam dnsrch
;; res_nsend to server orange.kame.net  2001:200:0:8002:203:47ff:fea5:3085: Protocol not supported
% 

This happens on both 4.8R and 5.1R. What's wrong with this failure?
Bug of FreeBSD or any configuration error of my machines?

---
KIMURA Yasuhiro
Mail: yasu at utahime.org
WWW:  http://www.utahime.org/