## page was renamed from DNS/watch-www/mext.go.jp
## page was renamed from DNS/watch/www/mext.go.jp
## page was renamed from DNS/watch/www.mext.go.jp
## page was renamed from DNS/www.mext.go.jp
Describe DNS/www.mext.go.jp here.

== www.mext.go.jp への道程 ==

$dnsq ns mext.go.jp
{{{
2 mext.go.jp:
127 bytes, 1+0+3+2 records, response, noerror
query: 2 mext.go.jp
authority: mext.go.jp 86400 NS dns.mext.go.jp
authority: mext.go.jp 86400 NS hstafw.mext.go.jp
authority: mext.go.jp 86400 NS sigw.sinet.ad.jp
additional: dns.mext.go.jp 86400 A 202.244.24.2
additional: hstafw.mext.go.jp 86400 A 202.241.4.6
}}}

$dnsq a www.mext.go.jp 202.244.24.2
{{{
1 www.mext.go.jp:
82 bytes, 1+0+2+0 records, response, noerror
query: 1 www.mext.go.jp
authority: www.mext.go.jp 86400 NS ns00.cdn.2iij.net
authority: www.mext.go.jp 86400 NS ns20.cdn.2iij.net
}}}

あれ、www.mext.go.jp は委譲されている。

$dnsq a www.mext.go.jp 202.241.4.6
{{{
1 www.mext.go.jp:
82 bytes, 1+0+2+0 records, response, noerror
query: 1 www.mext.go.jp
authority: www.mext.go.jp 86400 NS ns20.cdn.2iij.net
authority: www.mext.go.jp 86400 NS ns00.cdn.2iij.net
}}}

ns[02]0.cdn.2iij.net の A レコードは後回しにして、もう一台のNS(sigw.sinet.ad.jp)を追いかけてみると、
-----
$dnsq a sigw.sinet.ad.jp a.dns.jp
{{{
1 sigw.sinet.ad.jp:
104 bytes, 1+0+2+2 records, response, noerror
query: 1 sigw.sinet.ad.jp
authority: sinet.ad.jp 86400 NS jpnac.sinet.ad.jp
authority: sinet.ad.jp 86400 NS dns.sinet.ad.jp
additional: dns.sinet.ad.jp 86400 A 150.100.3.6
additional: jpnac.sinet.ad.jp 86400 A 150.100.1.6
}}}

150.100.3.6 が返事をしない。 (sinetの障害情報には記載されていないが。）
[[DNS/sinet.ad.jp]]

----
%dnsq a www.mext.go.jp ns20.cdn.2iij.net
{{{
1 www.mext.go.jp:
64 bytes, 1+2+0+0 records, response, authoritative, noerror
query: 1 www.mext.go.jp
answer: www.mext.go.jp 30 A 202.32.224.156
answer: www.mext.go.jp 30 A 202.32.225.156
}}}

%dnsq a www.mext.go.jp ns00.cdn.2iij.net
{{{
1 www.mext.go.jp:
64 bytes, 1+2+0+0 records, response, authoritative, noerror
query: 1 www.mext.go.jp
answer: www.mext.go.jp 30 A 203.180.164.156
answer: www.mext.go.jp 30 A 202.32.224.156
}}}

TTL が短いのはともかく、返事が異なる。
　特定のサーバの返事も変わるらしい。

21:03%dnsq a www.mext.go.jp ns00.cdn.2iij.net
{{{
1 www.mext.go.jp:
64 bytes, 1+2+0+0 records, response, authoritative, noerror
query: 1 www.mext.go.jp
answer: www.mext.go.jp 30 A 202.32.224.156
answer: www.mext.go.jp 30 A 202.32.225.156
}}}
21:04d%dnsq a www.mext.go.jp ns00.cdn.2iij.net
{{{
1 www.mext.go.jp:
64 bytes, 1+2+0+0 records, response, authoritative, noerror
query: 1 www.mext.go.jp
answer: www.mext.go.jp 30 A 203.180.164.156
answer: www.mext.go.jp 30 A 202.32.224.156
}}}

逆引きは設定されていない。

----

%dnsq ns www.mext.go.jp ns20.cdn.2iij.net
{{{
2 www.mext.go.jp:
82 bytes, 1+2+0+0 records, response, authoritative, noerror
query: 2 www.mext.go.jp
answer: www.mext.go.jp 60 NS ns20.cdn.2iij.net
answer: www.mext.go.jp 60 NS ns00.cdn.2iij.net
}}}
NSレコードのTTLが60というのもひどい。