Describe DNS/サーバ設定の調査/いくつかの例/icann.org here.

%dnsq ns icann.org a.root-servers.net                                   ~
2 icann.org:
429 bytes, 1+0+6+12 records, response, noerror
query: 2 icann.org
authority: org 172800 NS b2.org.afilias-nst.org
authority: org 172800 NS a2.org.afilias-nst.info
authority: org 172800 NS c0.org.afilias-nst.info
authority: org 172800 NS a0.org.afilias-nst.info
authority: org 172800 NS d0.org.afilias-nst.org
authority: org 172800 NS b0.org.afilias-nst.org
additional: a0.org.afilias-nst.info 172800 A 199.19.56.1
additional: a0.org.afilias-nst.info 172800 28 \040\001\005\000\000\016\000\000\000\000\000\000\000\000\000\001
additional: a2.org.afilias-nst.info 172800 A 199.249.112.1
additional: a2.org.afilias-nst.info 172800 28 \040\001\005\000\000@\000\000\000\000\000\000\000\000\000\001
additional: b0.org.afilias-nst.org 172800 A 199.19.54.1
additional: b0.org.afilias-nst.org 172800 28 \040\001\005\000\000\014\000\000\000\000\000\000\000\000\000\001
additional: b2.org.afilias-nst.org 172800 A 199.249.120.1
additional: b2.org.afilias-nst.org 172800 28 \040\001\005\000\000H\000\000\000\000\000\000\000\000\000\001
additional: c0.org.afilias-nst.info 172800 A 199.19.53.1
additional: c0.org.afilias-nst.info 172800 28 \040\001\005\000\000\013\000\000\000\000\000\000\000\000\000\001
additional: d0.org.afilias-nst.org 172800 A 199.19.57.1
additional: d0.org.afilias-nst.org 172800 28 \040\001\005\000\000\017\000\000\000\000\000\000\000\000\000\001

b2.org.afilias-nst.org 172800 A 199.249.120.1 にicann.orgについて問い合わせてみると、

%dnsq ns icann.org 199.249.120.1                                        ~
2 icann.org:
169 bytes, 1+0+5+2 records, response, noerror
query: 2 icann.org
authority: icann.org 86400 NS a.iana-servers.net
authority: icann.org 86400 NS b.iana-servers.org
authority: icann.org 86400 NS c.iana-servers.net
authority: icann.org 86400 NS d.iana-servers.net
authority: icann.org 86400 NS ns.icann.org
additional: b.iana-servers.org 86400 A 193.0.0.236
additional: ns.icann.org 86400 A 192.0.34.126

ここでもiana-servers.orgのAをつけてきます。

• orgのサーバだから、間違いとはいえないけれど、、、、

%dnsq ns icann.org 193.0.0.236                                          ~
2 icann.org:
301 bytes, 1+5+0+8 records, response, authoritative, noerror
query: 2 icann.org
answer: icann.org 86400 NS c.iana-servers.net
answer: icann.org 86400 NS ns.icann.org
answer: icann.org 86400 NS d.iana-servers.net
answer: icann.org 86400 NS b.iana-servers.org
answer: icann.org 86400 NS a.iana-servers.net
additional: a.iana-servers.net 28800 A 192.0.34.43
additional: b.iana-servers.org 28800 A 193.0.0.236
additional: b.iana-servers.org 28800 28 \040\001\006\020\002@\000\002\000\000\000\000\301\000\000\354
additional: c.iana-servers.net 28800 A 139.91.1.10
additional: c.iana-servers.net 28800 28 \040\001\006H,0\000\000\000\000\000\000\000\001\000\020
additional: d.iana-servers.net 28800 A 199.4.29.153
additional: d.iana-servers.net 28800 28 &\040\000\000.\340\000\002\000\000\000\000\000\000\001S
additional: ns.icann.org 21600 A 192.0.34.126

192.0.34.126の返答も同様です。

icann.org サーバに問い合わせているのに、iana-servers.net についての情報をつけられても信用していいものやら。