[6bone] Reverse lookup

[itojun@iijlab.net]

>>> host fec0:0:0:1::2 gives me:
>>> Host \[xFEC00000000000010000000000000002].ip6.arpa not found:
>>> 2(serverfail)
>> bitstring format is not used at this time, you must prefer the
>> nibble format, it works fine.
>In other words, the bug is in host(1), not in your dns server or its
>configuration.

	another thing is that you can't register site-local (fec0::/10) address
	into your DNS servers, unless you run two-faced DNS.

itojun