Unable to find any PTR-records for the specified domain/ip :(
Log
+000
Resolving PTR record of '2600:9000:21ff::'
+180
ERRNo PTR record availible DNS server 'x3.amazonaws.org' raised an NotExistentDomain error, while beeing queried for PTR-records on domain '0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.f.f.1.2.0.0.0.9.0.0.6.2.ip6.arpa'.