Robtex

Up: 13.33.32.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 13.33.36.0/23
Down right: 13.33.38.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
13.33.36.40	PTR	server-13-33-36-40.bos50.r.cloudfront.net
13.33.36.40	A	smabruderan-prj.slack.com
13.33.36.40	A	vivosqm.slack.com
13.33.36.152	PTR	server-13-33-36-152.sin2.r.cloudfront.net
13.33.36.152	A	server-13-33-36-152.bos50.r.cloudfront.net
13.33.36.179	A+PTR	server-13-33-36-179.bos50.r.cloudfront.net
13.33.36.181	A+PTR	server-13-33-36-181.bos50.r.cloudfront.net
13.33.37.43	A+PTR	server-13-33-37-43.bos50.r.cloudfront.net
13.33.37.66	A+PTR	server-13-33-37-66.bos50.r.cloudfront.net
13.33.37.89	A+PTR	server-13-33-37-89.bos50.r.cloudfront.net
13.33.37.157	A+PTR	server-13-33-37-157.bos50.r.cloudfront.net
13.33.37.174	A+PTR	server-13-33-37-174.bos50.r.cloudfront.net
13.33.37.180	A+PTR	server-13-33-37-180.bos50.r.cloudfront.net
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