1. watchA
akam.net からの返事には 真のglue と余計なA/AAAAが混在している。(sibling domain glueと呼ばれている。)
$ dig -t ns cc.keio.ac.jp @a4-65.akam.net. ; <<>> DiG 9.11.3-1ubuntu1.11-Ubuntu <<>> -t ns cc.keio.ac.jp @a4-65.akam.net. ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4990 ;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 6, ADDITIONAL: 13 ;; WARNING: recursion requested but not available ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;cc.keio.ac.jp. IN NS ;; AUTHORITY SECTION: cc.keio.ac.jp. 10800 IN NS ns0.sfc.keio.ac.jp. cc.keio.ac.jp. 10800 IN NS kogwy.cc.keio.ac.jp. cc.keio.ac.jp. 10800 IN NS ns.st.keio.ac.jp. cc.keio.ac.jp. 10800 IN NS ns.mita.keio.ac.jp. cc.keio.ac.jp. 10800 IN NS ns.hc.keio.ac.jp. cc.keio.ac.jp. 10800 IN NS ns.sc.keio.ac.jp. ;; ADDITIONAL SECTION: ns.mita.keio.ac.jp. 10800 IN AAAA 2001:df0:eb:2106::8 ns.st.keio.ac.jp. 10800 IN A 131.113.1.8 kogwy.cc.keio.ac.jp. 10800 IN AAAA 2001:df0:eb:8001::1 ns.mita.keio.ac.jp. 10800 IN A 131.113.192.8 ns.hc.keio.ac.jp. 10800 IN A 131.113.224.8 ns.hc.keio.ac.jp. 10800 IN AAAA 2001:df0:eb:4259::8 ns0.sfc.keio.ac.jp. 10800 IN AAAA 2001:200:1c0:1100::121 ns.sc.keio.ac.jp. 10800 IN A 131.113.191.8 ns.st.keio.ac.jp. 10800 IN AAAA 2001:df0:eb:8001::8 ns0.sfc.keio.ac.jp. 10800 IN A 133.27.4.121 ns.sc.keio.ac.jp. 10800 IN AAAA 2001:df0:eb:612d::191:8 kogwy.cc.keio.ac.jp. 10800 IN A 131.113.1.1 ;; Query time: 23 msec ;; SERVER: 72.246.46.65#53(72.246.46.65) ;; WHEN: Thu Jun 25 08:41:06 JST 2020 ;; MSG SIZE rcvd: 430
2. kogwy
余計なものはついていない。
- kogwy.cc.keio.ac.jp. 3600 IN A 131.113.1.1
$ dig -t ns cc.keio.ac.jp @kogwy.cc.keio.ac.jp. ; <<>> DiG 9.11.3-1ubuntu1.11-Ubuntu <<>> -t ns cc.keio.ac.jp @kogwy.cc.keio.ac.jp. ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20448 ;; flags: qr aa rd; QUERY: 1, ANSWER: 6, AUTHORITY: 0, ADDITIONAL: 1 ;; WARNING: recursion requested but not available ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;cc.keio.ac.jp. IN NS ;; ANSWER SECTION: cc.keio.ac.jp. 3600 IN NS ns.mita.keio.ac.jp. cc.keio.ac.jp. 3600 IN NS ns.hc.keio.ac.jp. cc.keio.ac.jp. 3600 IN NS kogwy.cc.keio.ac.jp. cc.keio.ac.jp. 3600 IN NS ns0.sfc.keio.ac.jp. cc.keio.ac.jp. 3600 IN NS ns.sc.keio.ac.jp. cc.keio.ac.jp. 3600 IN NS ns.st.keio.ac.jp. ;; Query time: 18 msec ;; SERVER: 131.113.1.1#53(131.113.1.1) ;; WHEN: Thu Jun 25 08:46:00 JST 2020 ;; MSG SIZE rcvd: 166
3. しかし
これはkogwy.cc が cc, hc, mita, sc, sfc, st のゾーンを持つからである。(keio.ac.jp ゾーンも)
$ dig -t a ns.mita.keio.ac.jp @kogwy.cc.keio.ac.jp. ; <<>> DiG 9.11.3-1ubuntu1.11-Ubuntu <<>> -t a ns.mita.keio.ac.jp @kogwy.cc.keio.ac.jp. ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 36951 ;; 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: 4096 ;; QUESTION SECTION: ;ns.mita.keio.ac.jp. IN A ;; ANSWER SECTION: ns.mita.keio.ac.jp. 86400 IN A 131.113.192.8 ;; Query time: 19 msec ;; SERVER: 131.113.1.1#53(131.113.1.1) ;; WHEN: Thu Jun 25 08:49:00 JST 2020 ;; MSG SIZE rcvd: 63