Robtex

Up: 177.72.240.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 177.72.240.0/23
Down right: 177.72.242.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
177.72.243.194	A+PTR	gru-a-orca.amazon.com
177.72.243.194	A	gru-orca-bak.amazon.com
177.72.243.198	A+PTR	gru-b-orca.amazon.com
177.72.243.198	A	gru-orca-bak.amazon.com
177.72.243.198	A	vpn.ivpn.amazon-corp.com