BIND 9 AAAA record problems
JINMEI Tatuya / 神明達哉
jinmei at isl.rdc.toshiba.co.jp
Tue Jun 29 07:37:47 UTC 2004
>>>>> On Mon, 28 Jun 2004 14:55:32 +0000,
>>>>> "Todd T. Fries" <todd at fries.net> said:
> Why is it a bad thing to start out with AAAA? Proper getaddrinfo()
> implementations should query first an AAAA then an A record for names,
> so that applications can then connect to whatever is appropriate.
> It is all part of a `seamless' transition to v6 that has started, albiet
> slowly.
> For whatever it is worth, the libc in OpenBSD behaves this way, and I
> quite am pleased that it does.
> It's not a bug, it's a feature ;-)
In general and in theory, I agree. But we should also note some
practical issues in the real world. To name a few:
- there are some misbehaving authoritative servers against AAAA
queries. See draft-ietf-dnsop-bad-dns-res-02.txt for more details.
- I've noticed some applications do not implement the proper fallback
mechanisms from IPv6 to IPv4. Some do not fall back to A queries
when AAAA queries fail (with "NONAME"). Some do not try to connect
the IPv4 addresses when the attempt to connect to the IPv6 addresses
fails. I see mozilla/firefox show this behavior with its internal
resolver routines.
JINMEI, Tatuya
Communication Platform Lab.
Corporate R&D Center, Toshiba Corp.
jinmei at isl.rdc.toshiba.co.jp
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