There seems to be a problem with dns delegation for the nlede01 PoP. I was having an issue getting Reversed DNS working for my subnet (2001:7b8:1507::/48). I kept getting the "Unable to find primary nameserver (SOA)" error. Using dig +trace I found that my DNS server is not getting queried. Even more, the sixxs.net DNS servers are not queried for my subnet. Here are my findings. nlede01 subnet 2001:7b8:300::/40 of size /48, nicely goes through sixxs.net: dig +trace 0.0.3.0.8.b.7.0.1.0.0.2.ip6.arpa nlede01 subnet 2001:7b8:1500::/40 of size /48, ends at sixxs.net: dig +trace 0.0.5.1.8.b.7.0.1.0.0.2.ip6.arpa my subnet, does not go through sixxs.net, but ends at nsauth*.bit.nl (owner of the PoP): dig +trace 7.0.5.1.8.b.7.0.1.0.0.2.ip6.arpa Even if there was a problem with my DNS setup, shouldn't it still end at sixxs.net DNS servers?