Robtex

Up: 13.33.38.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 13.33.39.0/25
Down right: 13.33.39.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
13.33.39.47	A+PTR	server-13-33-39-47.bos50.r.cloudfront.net
13.33.39.61	A+PTR	server-13-33-39-61.bos50.r.cloudfront.net
13.33.39.129	PTR	server-13-33-39-129.sin2.r.cloudfront.net
13.33.39.129	A	win-help-915.s3-accelerate.amazonaws.com
13.33.39.129	A	win-help-918.s3-accelerate.amazonaws.com
13.33.39.204	A+PTR	server-13-33-39-204.bos50.r.cloudfront.net