1. web サーバのIPv6対応

AAAAレコードがあっても、その先がredirectであるケース (redirect*.jpdirect.jpなど）では そこに(IPv6で）アクセスできないことが多い。

%dnsqr6 any www.woodpecker.jp 

255 www.woodpecker.jp:
160 bytes, 1+2+3+0 records, response, noerror
query: 255 www.woodpecker.jp
answer: www.woodpecker.jp 86400 A 202.11.16.173
answer: www.woodpecker.jp 86400 AAAA 2001:df0:8:7::30
authority: woodpecker.jp 86400 NS redirect1.jpdirect.jp
authority: woodpecker.jp 86400 NS redirect3.jpdirect.jp
authority: woodpecker.jp 86400 NS redirect2.jpdirect.jp

%dnsq aaaa www.woodpecker.jp redirect1.jpdirect.jp 

28 www.woodpecker.jp:
144 bytes, 1+1+3+0 records, response, authoritative, noerror
query: 28 www.woodpecker.jp
answer: www.woodpecker.jp 86400 28 \040\001\015\360\000\010\000\007\000\000\000\000\000\000\0000
authority: woodpecker.jp 86400 NS redirect3.jpdirect.jp
authority: woodpecker.jp 86400 NS redirect2.jpdirect.jp
authority: woodpecker.jp 86400 NS redirect1.jpdirect.jp

10:07m6%wget -6 http://www.woodpecker.jp/ 

--2011-09-14 10:08:02--  http://www.woodpecker.jp/
Resolving www.woodpecker.jp... 2001:df0:8:7::30
Connecting to www.woodpecker.jp|2001:df0:8:7::30|:80... connected.
HTTP request sent, awaiting response... 302 Found
Location: http://woodpecker.co.jp [following]
--2011-09-14 10:08:02--  http://woodpecker.co.jp/
Resolving woodpecker.co.jp... failed: hostname nor servname provided, or not known.
wget: unable to resolve host address `woodpecker.co.jp'

2. IPv4ではアクセスできる

6%wget http://www.woodpecker.jp/ 

--2011-09-14 10:13:05--  http://www.woodpecker.jp/
Resolving www.woodpecker.jp... 202.11.16.173, 2001:df0:8:7::30
Connecting to www.woodpecker.jp|202.11.16.173|:80... connected.
HTTP request sent, awaiting response... 302 Found
Location: http://woodpecker.co.jp [following]
--2011-09-14 10:13:05--  http://woodpecker.co.jp/
Resolving woodpecker.co.jp... 211.13.204.3
Connecting to woodpecker.co.jp|211.13.204.3|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 6479 (6.3K) [text/html]
Saving to: `index.html'

100%[======================================>] 6,479       --.-K/s   in 0.002s  

2011-09-14 10:13:05 (4.08 MB/s) - `index.html' saved [6479/6479]