Originated from ARPANET, The .arpa domain is designated to be used exclusively for Internet-infrastructure purposes [1], while `.ip6.arpa` is used for rDNS in IPv6 [2]. The domain was designed to host PTR records. However an LIR [3] has the access to the NS server settings of the allocated IPv6 addresses, thus configuring an A/AAAA record allows one to use the subdomains as a website. [1]: https://www.iana.org/domains/arpa [2]: https://datatracker.ietf.org/doc/html/rfc3152 [3]: https://www.apnic.net/manage-ip/manage-resources/address-management-objectives-2/address-management-objectives/ $ dig +trace -t ANY yongting.0.2.0.0.1.0.4.2.ip6.arpa ; <<>> DiG 9.18.24-1-Debian <<>> +trace -t ANY yongting.0.2.0.0.1.0.4.2.ip6.arpa ;; global options: +cmd . 1086 IN NS i.root-servers.net. . 1086 IN NS l.root-servers.net. . 1086 IN NS m.root-servers.net. . 1086 IN NS g.root-servers.net. . 1086 IN NS d.root-servers.net. . 1086 IN NS b.root-servers.net. . 1086 IN NS f.root-servers.net. . 1086 IN NS e.root-servers.net. . 1086 IN NS a.root-servers.net. . 1086 IN NS h.root-servers.net. . 1086 IN NS c.root-servers.net. . 1086 IN NS j.root-servers.net. . 1086 IN NS k.root-servers.net. ;; Received 239 bytes from 223.5.5.5#53(223.5.5.5) in 8 ms ip6.arpa. 172800 IN NS a.ip6-servers.arpa. ip6.arpa. 172800 IN NS b.ip6-servers.arpa. ip6.arpa. 172800 IN NS c.ip6-servers.arpa. ip6.arpa. 172800 IN NS d.ip6-servers.arpa. ip6.arpa. 172800 IN NS e.ip6-servers.arpa. ip6.arpa. 172800 IN NS f.ip6-servers.arpa. ip6.arpa. 86400 IN DS 13880 8 2 068554EFCB5861F42AF93EF8E79C442A86C16FC5652E6B6D2419ED52 7F344D17 ip6.arpa. 86400 IN DS 45094 8 2 E6B54E0A20CE1EDBFCB6879C02F5782059CECB043A31D804A04AFA51 AF01D5FB ip6.arpa. 86400 IN DS 64060 8 2 8A11501086330132BE2C23F22DEDF0634AD5FF668B4AA1988E172C6A 2A4E5F7B ip6.arpa. 86400 IN RRSIG DS 8 2 86400 20240623060000 20240610050000 43060 arpa. 0Fd0UasA5K4+Rc5iKK+Z8y+ZTf8EEiOkGp8qCKIYbzS/C1dLglJ4v6DI 3CrIGaACXNeG6q7K1jEZbb4LCplc2ugDOIQi6K9aSHZWFgqGFBhMxybI d0A0wkASjuOAMkILREc2Z70D0ahnpPb2m5/LgHT5BWX5QatefZgIXugv UXSDaKxxSo8Y5wyH9kGCkTvgfC9CIWhVk4LILnwbq27/MduAuM1aWasu yVBmFQ0JiI709o6lqEZy61V7o0uRQW7rBR2U0eHtp2rDxSYcSJobhc66 kWEOFsKF7ETSAZXG2U8mpizU8Gtwmzo43Qo47AQ/oZcXcwKf1vgnZLoj KU2djA== ;; Received 870 bytes from 199.7.91.13#53(d.root-servers.net) in 248 ms 0.4.2.ip6.arpa. 86400 IN NS ns3.lacnic.net. 0.4.2.ip6.arpa. 86400 IN NS ns2.apnic.net. 0.4.2.ip6.arpa. 86400 IN NS apnic.authdns.ripe.net. 0.4.2.ip6.arpa. 86400 IN NS ns1.apnic.net. 0.4.2.ip6.arpa. 86400 IN NS rirns.arin.net. 0.4.2.ip6.arpa. 86400 IN DS 41754 13 2 A8958987947D4A7030430F6104AF7201947551B48F144DB952A9B25F 37E77193 0.4.2.ip6.arpa. 86400 IN RRSIG DS 8 5 86400 20240629125546 20240608202947 49278 ip6.arpa. aKaddatF/Rtsv99Oj/pUh8V91dKBoboi9lfnyddYajBjAkyWT1uQ2SoD iLrO+vDTf1LxJXn5oYiSMpAJQpzOjl1W50XTPY/2bsz6NgeZ8fKG9RJc c+nKVDobRnv++RICNfkyHie5tPb040soIInQvE1+VcRuA4418de1hmtJ hrE= ;; Received 457 bytes from 203.119.86.101#53(e.ip6-servers.arpa) in 56 ms 0.2.0.0.1.0.4.2.ip6.arpa. 86400 IN NS 53.oih.me. 0.2.0.0.1.0.4.2.ip6.arpa. 86400 IN NS 53.tianhai.link. 3rve51dtj3om3rh03gui697e19hp12fg.0.4.2.ip6.arpa. 3600 IN NSEC3 1 0 0 20A4B14399F2F6E6 3S5TQBULJCOCC78295QGPTL8MOTVOLDR NS 3rve51dtj3om3rh03gui697e19hp12fg.0.4.2.ip6.arpa. 3600 IN RRSIG NSEC3 13 6 3600 20240622065918 20240607052918 53404 0.4.2.ip6.arpa. xvIgMp4J8lVGuP/I1LOhBXJzAO1GIKIlxlffP1krIF0OdFFN9uTJtdI/ PqVXI3NGBLcf9pEVwISbJSHa5g/U+A== ;; Received 348 bytes from 203.119.42.53#53(ns1.apnic.net) in 140 ms yongting.0.2.0.0.1.0.4.2.ip6.arpa. 3600 IN A 1.1.1.1 ;; Received 94 bytes from 45.9.11.10#53(53.oih.me) in 100 ms