Unable to find any PTR-records for the specified domain/ip :(
Log
+000
Resolving PTR record of '207.21.0.0'
+130
ERRNo PTR record availible DNS server 'auth23.ns.gin.ntt.net' raised an NotExistentDomain error, while beeing queried for PTR-records on domain '0.0.21.207.in-addr.arpa'.