Unable to find any PTR-records for the specified domain/ip :(
Log
+000
Resolving PTR record of '216.221.164.0'
+248
ERRNo PTR record availible DNS server 'x2.amazonaws.com' raised an NotExistentDomain error, while beeing queried for PTR-records on domain '0.164.221.216.in-addr.arpa'.