PTR lookup of 'amazon.com'

No PTR record :(

Unable to find any PTR-records for the specified domain/ip :(

IP lookup

amazon.com
A
52.94.236.248
amazon.com
A
54.239.28.85
A
205.251.242.103

PTR answers

205.251.242.103
PTR
s3-console-us-standard.console.aws.amazon.com

Log

+000
  • Resolving host 'amazon.com'
+046
  • IP's found: amazon.com (205.251.242.103), amazon.com (52.94.236.248), amazon.com (54.239.28.85)
+046
  • Multiple IPs to check - public DNS-resolvers will be used (Google and OpenDNS)
+046
  • Resolving PTR record of '205.251.242.103'
+069
  • PTR-record resolved in a total of 21ms. Responding DNS-server: 8.8.4.4.
+069
  • Resolving PTR record of '52.94.236.248'
+094
  • ERRNo PTR record availible
    DNS server '208.67.220.220' raised an NotExistentDomain error, while beeing queried for PTR-records on domain '248.236.94.52.in-addr.arpa'.
+094
  • Resolving PTR record of '54.239.28.85'
+113
  • ERRNo PTR record availible
    DNS server '8.8.8.8' raised an NotExistentDomain error, while beeing queried for PTR-records on domain '85.28.239.54.in-addr.arpa'.