Robtex

Up: 54.239.192.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 54.239.196.0/23
Down right: 54.239.198.0/23

IP	Type	Hostname
54.239.196.5	PTR	server-54-239-196-5.nrt12.r.cloudfront.net
54.239.196.12	A+PTR	server-54-239-196-12.nrt12.r.cloudfront.net
54.239.196.43	A+PTR	server-54-239-196-43.nrt12.r.cloudfront.net
54.239.196.77	A+PTR	server-54-239-196-77.nrt12.r.cloudfront.net
54.239.196.82	A+PTR	server-54-239-196-82.nrt12.r.cloudfront.net
54.239.196.140	A+PTR	server-54-239-196-140.nrt12.r.cloudfront.net
54.239.196.157	PTR	server-54-239-196-157.nrt12.r.cloudfront.net
54.239.196.159	A+PTR	server-54-239-196-159.nrt12.r.cloudfront.net
54.239.196.169	PTR	server-54-239-196-169.nrt12.r.cloudfront.net