Hi, Seems that rdns delegation for 7.9.1.0.0.a.6.0.1.0.0.2.ip6.arpa is not working, it should be delegated to fns1.42.pl : dig +trace 7.9.1.0.0.a.6.0.1.0.0.2.ip6.arpa. ns ; <<>> DiG 9.7.2-P3 <<>> +trace 7.9.1.0.0.a.6.0.1.0.0.2.ip6.arpa. ns ;; global options: +cmd . 515485 IN NS c.root-servers.net. . 515485 IN NS e.root-servers.net. . 515485 IN NS d.root-servers.net. . 515485 IN NS l.root-servers.net. . 515485 IN NS k.root-servers.net. . 515485 IN NS b.root-servers.net. . 515485 IN NS g.root-servers.net. . 515485 IN NS a.root-servers.net. . 515485 IN NS j.root-servers.net. . 515485 IN NS i.root-servers.net. . 515485 IN NS f.root-servers.net. . 515485 IN NS h.root-servers.net. . 515485 IN NS m.root-servers.net. ;; Received 472 bytes from 62.179.1.63#53(62.179.1.63) in 13 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. ;; Received 430 bytes from 2001:500:3::42#53(l.root-servers.net) in 63 ms 6.0.1.0.0.2.ip6.arpa. 84600 IN NS sunic.sunet.se. 6.0.1.0.0.2.ip6.arpa. 84600 IN NS munnari.oz.au. 6.0.1.0.0.2.ip6.arpa. 84600 IN NS tinnie.arin.net. 6.0.1.0.0.2.ip6.arpa. 84600 IN NS ns-pri.ripe.net. 6.0.1.0.0.2.ip6.arpa. 84600 IN NS sec1.apnic.net. 6.0.1.0.0.2.ip6.arpa. 84600 IN NS sec3.apnic.net. 6.0.1.0.0.2.ip6.arpa. 84600 IN NS ns3.nic.fr. 6.0.1.0.0.2.ip6.arpa. 84600 IN NS sns-pb.isc.org. ;; Received 300 bytes from 2001:500:13::73#53(a.ip6-servers.arpa) in 152 ms 0.a.6.0.1.0.0.2.ip6.arpa. 172800 IN NS ns1.net.icm.edu.pl. 0.a.6.0.1.0.0.2.ip6.arpa. 172800 IN NS ns2.net.icm.edu.pl. ;; Received 100 bytes from 2001:dc0:1:0:4777::140#53(sec3.apnic.net) in 307 ms 1.0.0.a.6.0.1.0.0.2.ip6.arpa. 14400 IN NS ns4.sixxs.net. 1.0.0.a.6.0.1.0.0.2.ip6.arpa. 14400 IN NS ns2.sixxs.net. 1.0.0.a.6.0.1.0.0.2.ip6.arpa. 14400 IN NS ns1.sixxs.net. 1.0.0.a.6.0.1.0.0.2.ip6.arpa. 14400 IN NS ns3.sixxs.net. ;; Received 131 bytes from 193.219.28.51#53(ns2.net.icm.edu.pl) in 12 ms 1.0.0.a.6.0.1.0.0.2.ip6.arpa. 604800 IN SOA localhost. hostmaster.sixxs.net. 2011020102 10800 3600 2419200 604800 ;; Received 115 bytes from 2001:838:1:1:210:dcff:fe20:7c7c#53(ns4.sixxs.net) in 71 ms Best Regards, TG