以下のように問い合わせる。
- 答えを知っていそうなネームサーバに問い合わせる。（最初はrootから）
-
返事を確認
- ANSWER SECTION を確認し、もしアドレスが含まれていたら完了
- AUTHORITY SECTION を確認し、NSレコードが含まれていれば、次に問い合わせるべきベームサーバのドメイン名を知ることができる。
- ADDITIONAL SECTIONを確認し、AUTHORITY SECTIONにあったNSが"glue record"に含まれていれば次に問い合わせるべきネームサーバのIP Addressがわかる。1へ(新たなネームサーバに問い合わせる)。
もし、glue recordがなければ、AUTHORITY SECTIONのNSをまず調べる。調べたら1へ(新たなネームサーバに問い合わせる)。 - もし、AUTHORITY SECTIONでNSが含まれていなければ困った！失敗！
wikipedia.orgを名前解決してみる。
まず、rootに聞く。
% dig wikipedia.org @m.root-servers.net. ; <<>> DiG 9.10.6 <<>> wikipedia.org @m.root-servers.net. ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 32887 ;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 6, ADDITIONAL: 13 ;; WARNING: recursion requested but not available ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 1232 ;; QUESTION SECTION: ;wikipedia.org. IN A ;; AUTHORITY SECTION: org. 172800 IN NS a0.org.afilias-nst.info. org. 172800 IN NS b2.org.afilias-nst.org. org. 172800 IN NS b0.org.afilias-nst.org. org. 172800 IN NS a2.org.afilias-nst.info. org. 172800 IN NS c0.org.afilias-nst.info. org. 172800 IN NS d0.org.afilias-nst.org. ;; ADDITIONAL SECTION: d0.org.afilias-nst.org. 172800 IN A 199.19.57.1 c0.org.afilias-nst.info. 172800 IN A 199.19.53.1 b2.org.afilias-nst.org. 172800 IN A 199.249.120.1 b0.org.afilias-nst.org. 172800 IN A 199.19.54.1 a2.org.afilias-nst.info. 172800 IN A 199.249.112.1 a0.org.afilias-nst.info. 172800 IN A 199.19.56.1 d0.org.afilias-nst.org. 172800 IN AAAA 2001:500:f::1 c0.org.afilias-nst.info. 172800 IN AAAA 2001:500:b::1 b2.org.afilias-nst.org. 172800 IN AAAA 2001:500:48::1 b0.org.afilias-nst.org. 172800 IN AAAA 2001:500:c::1 a2.org.afilias-nst.info. 172800 IN AAAA 2001:500:40::1 a0.org.afilias-nst.info. 172800 IN AAAA 2001:500:e::1 ;; Query time: 13 msec ;; SERVER: 2001:dc3::35#53(2001:dc3::35) ;; WHEN: Sun Sep 25 13:57:37 JST 2022 ;; MSG SIZE rcvd: 447
ADDITIONAL SECTION に glue recordsが含まれていたためそのうちひとつ
d0.org.afilias-nst.org. 172800 IN A 199.19.57.1
から次は199.19.57.1に問い合わせる。
% dig wikipedia.org @199.19.57.1 ; <<>> DiG 9.10.6 <<>> wikipedia.org @199.19.57.1 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 24037 ;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 3, ADDITIONAL: 4 ;; WARNING: recursion requested but not available ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 1232 ;; QUESTION SECTION: ;wikipedia.org. IN A ;; AUTHORITY SECTION: wikipedia.org. 3600 IN NS ns2.wikimedia.org. wikipedia.org. 3600 IN NS ns1.wikimedia.org. wikipedia.org. 3600 IN NS ns0.wikimedia.org. ;; ADDITIONAL SECTION: ns0.wikimedia.org. 3600 IN A 208.80.154.238 ns1.wikimedia.org. 3600 IN A 208.80.153.231 ns2.wikimedia.org. 3600 IN A 91.198.174.239 ;; Query time: 12 msec ;; SERVER: 199.19.57.1#53(199.19.57.1) ;; WHEN: Sun Sep 25 13:57:47 JST 2022 ;; MSG SIZE rcvd: 154
ADDITIONAL SECTION に glue recordsが含まれていたためそのうちひとつ
ns0.wikimedia.org. 3600 IN A 208.80.154.238
から208.80.154.238に問い合わせる。
% dig wikipedia.org @208.80.154.238 ; <<>> DiG 9.10.6 <<>> wikipedia.org @208.80.154.238 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 63701 ;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1 ;; WARNING: recursion requested but not available ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 1024 ;; QUESTION SECTION: ;wikipedia.org. IN A ;; ANSWER SECTION: wikipedia.org. 600 IN A 103.102.166.224 ;; Query time: 184 msec ;; SERVER: 208.80.154.238#53(208.80.154.238) ;; WHEN: Sun Sep 25 13:58:03 JST 2022 ;; MSG SIZE rcvd: 58
そして名前解決をすることができた！
;; ANSWER SECTION: wikipedia.org. 600 IN A 103.102.166.224
dig +trace すると再帰的に問い合わせる様子が見える。
% dig wikipedia.org. +trace ; <<>> DiG 9.10.6 <<>> wikipedia.org. +trace ;; global options: +cmd . 280571 IN NS b.root-servers.net. . 280571 IN NS f.root-servers.net. . 280571 IN NS m.root-servers.net. . 280571 IN NS g.root-servers.net. . 280571 IN NS a.root-servers.net. . 280571 IN NS j.root-servers.net. . 280571 IN NS d.root-servers.net. . 280571 IN NS h.root-servers.net. . 280571 IN NS l.root-servers.net. . 280571 IN NS e.root-servers.net. . 280571 IN NS c.root-servers.net. . 280571 IN NS i.root-servers.net. . 280571 IN NS k.root-servers.net. . 280571 IN RRSIG NS 8 0 518400 20221005040000 20220922030000 20826 . DO8gA3Mjxp+8mxytLZ0ITfEjQcb0O1QUO2n7igWF7D/xnbK7HjHJRHc0 3m3mAXz0ZuFdx7i8A+A1fhhhUkvz74DA+zTfImByVRr9/zvF2nG+P5we ZSJNJ00y5/+/88bIRpVb5o3jeYVzKzIP46pfGQ68N8D9qaHVS4syhUma ylq+FlrFMW0qfhcIWXLLp3giqd7reD6w94Pyk+V9rblYO4zdiwVx99EX hVha/+6/4kiPa6C7SIT9vt9RsS3IhkYJtWSXecU/5hji6mbY250B7ipi vXVn7e8JUss7snW+0D1OCmuSLRpM/DY4uNuzwYwW83ywTSalG6BdUcp0 agS28w== ;; Received 525 bytes from 240b:10:b420:3c00:5a52:8aff:fe57:b959#53(240b:10:b420:3c00:5a52:8aff:fe57:b959) in 17 ms org. 172800 IN NS b0.org.afilias-nst.org. org. 172800 IN NS b2.org.afilias-nst.org. org. 172800 IN NS c0.org.afilias-nst.info. org. 172800 IN NS d0.org.afilias-nst.org. org. 172800 IN NS a0.org.afilias-nst.info. org. 172800 IN NS a2.org.afilias-nst.info. org. 86400 IN DS 26974 8 2 4FEDE294C53F438A158C41D39489CD78A86BEB0D8A0AEAFF14745C0D 16E1DE32 org. 86400 IN RRSIG DS 8 1 86400 20221007160000 20220924150000 20826 . ZsBhfjLoUwkO1rC8+cqrs+JF1fCwQhXnTkEU+K4a0k49klJ9dzge2OrM 0+B/CcZ3wku4hyQrmRUXzfkESepx2tVvInW9PeGuHS5O1Ub++kui5Hw9 mn4a7E6QeCdeW1A0p0hC3N0K90crEKMNnoTUj4hlCH4SdUh1gvnl8yuS GNK6MqzI18JNyv3lNKhZJGypUXUy24gw8Uf0RvCXn22ndX9A9Kib55zD WFHxhW2jKqp12QTULgQOKR2/PyUVIZjE6QIPQpIpBK2bWokMv0XcJv2h VF0Hl4QEkeq59I2Qs04Y7c/hE5ZpITCE7kSV/aMHMcACqCiLx7bQY51C JTsGuQ== ;; Received 782 bytes from 2001:dc3::35#53(m.root-servers.net) in 12 ms wikipedia.org. 3600 IN NS ns0.wikimedia.org. wikipedia.org. 3600 IN NS ns1.wikimedia.org. wikipedia.org. 3600 IN NS ns2.wikimedia.org. gdtpongmpok61u9lvnipqor8lra9l4t0.org. 3600 IN NSEC3 1 1 0 332539EE7F95C32A GDTREA8KMJ2RNEQEN4M2OGJ26KFSUKJ7 NS SOA RRSIG DNSKEY NSEC3PARAM gdtpongmpok61u9lvnipqor8lra9l4t0.org. 3600 IN RRSIG NSEC3 8 2 3600 20221016050244 20220925040244 56124 org. cr4LvNKu3sqDukgIMyPf57HDfZONHGCelMlTsKXZQW/2DsWnzig6gjwJ yUwz4ht5y8xVWOTk/aaVlwitoXvImGuE5asNt5XRQnTIQRtfhuXoasCt 9h6tTKcI6hb04uTX0a1+sVZ303keKfCNqhO+70KWcppbrnlf+ktYvg5q NWM= tpeahq77pcfqu9h00c3mh570ah1f4g65.org. 3600 IN NSEC3 1 1 0 332539EE7F95C32A TPEESGJUPU0G7LLLUQEA296C6EAUG5AU NS DS RRSIG tpeahq77pcfqu9h00c3mh570ah1f4g65.org. 3600 IN RRSIG NSEC3 8 2 3600 20221008152354 20220917142354 56124 org. fdnmYd7gnrhlwf0xkHHmybh/CheOIGWo/hIJ19En1f0xF6Ldf7sjitzZ PZpiwj0pQKRX4rQoJ6DBzBT/N9hdMzvzgJ4eK5GukwG6Qf4knPUnqZ36 zWqyQtqm3HEu+wXqmw+TI14p8tljdvqCemN0qNMKbz2ZhiBiiLHgxQ// A18= ;; Received 655 bytes from 199.19.56.1#53(a0.org.afilias-nst.info) in 12 ms wikipedia.org. 600 IN A 103.102.166.224 ;; Received 58 bytes from 208.80.153.231#53(ns1.wikimedia.org) in 151 ms
