Robtex

Up: 173.20.72.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 173.20.72.0/23
Down right: 173.20.74.0/23

IP	Type	Hostname
173.20.72.0	PTR	173-20-72-0.client.mchsi.com
173.20.72.32	A+PTR	173-20-72-32.client.mchsi.com
173.20.72.67	A+PTR	173-20-72-67.client.mchsi.com
173.20.72.109	A+PTR	173-20-72-109.client.mchsi.com
173.20.72.164	A	www.enterportal.net
173.20.72.171	A+PTR	173-20-72-171.client.mchsi.com
173.20.72.184	A+PTR	173-20-72-184.client.mchsi.com
173.20.73.239	PTR	173-20-73-239.client.mchsi.com
173.20.74.96	PTR	173-20-74-96.client.mchsi.com
173.20.74.181	A	lagrangesithlord.com
173.20.75.35	A	173-20-75-35.client.mchsi.com