Unable to find any PTR-records for the specified domain/ip :(
Log
+000
Resolving PTR record of '2600:1f21::'
+193
ERRNo PTR record availible DNS server 'x2.amazonaws.com' raised an NotExistentDomain error, while beeing queried for PTR-records on domain '0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.2.f.1.0.0.6.2.ip6.arpa'.