Unable to find any PTR-records for the specified domain/ip :(
Log
+000
Resolving PTR record of '129.33.138.0'
+235
ERRNo PTR record availible DNS server 'ns1.silverpop.com' raised an NotExistentDomain error, while beeing queried for PTR-records on domain '0.138.33.129.in-addr.arpa'.