Robtex

Up: 173.21.80.0/20
Can't show all results, try to descend to a more specific CIDR
Down left: 173.21.80.0/22
Down right: 173.21.84.0/22
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
173.21.80.0	A+PTR	173-21-80-0.client.mchsi.com
173.21.80.1	A+PTR	173-21-80-1.client.mchsi.com
173.21.80.3	A+PTR	173-21-80-3.client.mchsi.com
173.21.80.4	A	173-21-80-4.client.mchsi.com
173.21.80.13	A	173-21-80-13.client.mchsi.com
173.21.80.19	A+PTR	173-21-80-19.client.mchsi.com
173.21.80.20	A	173-21-80-20.client.mchsi.com
173.21.80.21	A	173-21-80-21.client.mchsi.com
173.21.80.25	A+PTR	173-21-80-25.client.mchsi.com
173.21.80.26	A+PTR	173-21-80-26.client.mchsi.com
173.21.80.30	A	173-21-80-30.client.mchsi.com
173.21.80.34	A+PTR	173-21-80-34.client.mchsi.com
173.21.80.36	A	173-21-80-36.client.mchsi.com
173.21.80.39	A	173-21-80-39.client.mchsi.com
173.21.80.40	A+PTR	173-21-80-40.client.mchsi.com
173.21.80.46	A	173-21-80-46.client.mchsi.com
173.21.80.53	A	173-21-80-53.client.mchsi.com
173.21.80.54	A	173-21-80-54.client.mchsi.com
173.21.80.62	A	173-21-80-62.client.mchsi.com
173.21.80.69	A	173-21-80-69.client.mchsi.com
173.21.80.70	A	173-21-80-70.client.mchsi.com
173.21.80.73	A+PTR	173-21-80-73.client.mchsi.com
173.21.80.76	A	173-21-80-76.client.mchsi.com
173.21.80.81	A+PTR	173-21-80-81.client.mchsi.com
173.21.80.89	A+PTR	173-21-80-89.client.mchsi.com
173.21.80.96	A+PTR	173-21-80-96.client.mchsi.com
173.21.80.97	A+PTR	173-21-80-97.client.mchsi.com
173.21.80.109	A	173-21-80-109.client.mchsi.com
173.21.80.115	A+PTR	173-21-80-115.client.mchsi.com
173.21.80.119	A	173-21-80-119.client.mchsi.com
173.21.80.127	A	173-21-80-127.client.mchsi.com
173.21.80.128	A+PTR	173-21-80-128.client.mchsi.com
173.21.80.133	A	173-21-80-133.client.mchsi.com
173.21.80.139	A+PTR	173-21-80-139.client.mchsi.com
173.21.80.141	A	173-21-80-141.client.mchsi.com
173.21.80.142	A	173-21-80-142.client.mchsi.com
173.21.80.143	A	173-21-80-143.client.mchsi.com
173.21.80.145	A+PTR	173-21-80-145.client.mchsi.com
173.21.80.146	A+PTR	173-21-80-146.client.mchsi.com
173.21.80.149	A	173-21-80-149.client.mchsi.com
173.21.80.151	A	173-21-80-151.client.mchsi.com
173.21.80.156	A	173-21-80-156.client.mchsi.com
173.21.80.165	A	173-21-80-165.client.mchsi.com
173.21.80.168	A+PTR	173-21-80-168.client.mchsi.com
173.21.80.169	A+PTR	173-21-80-169.client.mchsi.com
173.21.80.171	A+PTR	173-21-80-171.client.mchsi.com
173.21.80.174	A	173-21-80-174.client.mchsi.com
173.21.80.176	A+PTR	173-21-80-176.client.mchsi.com
173.21.80.178	A+PTR	173-21-80-178.client.mchsi.com
173.21.80.179	A+PTR	173-21-80-179.client.mchsi.com
173.21.80.181	A	173-21-80-181.client.mchsi.com
173.21.80.190	A	173-21-80-190.client.mchsi.com
173.21.80.192	A+PTR	173-21-80-192.client.mchsi.com
173.21.80.194	A+PTR	173-21-80-194.client.mchsi.com
173.21.80.200	A+PTR	173-21-80-200.client.mchsi.com
173.21.80.203	A+PTR	173-21-80-203.client.mchsi.com
173.21.80.205	A	173-21-80-205.client.mchsi.com
173.21.80.206	A	173-21-80-206.client.mchsi.com
173.21.80.209	A+PTR	173-21-80-209.client.mchsi.com
173.21.80.233	A+PTR	173-21-80-233.client.mchsi.com
173.21.80.234	A+PTR	173-21-80-234.client.mchsi.com
173.21.80.236	A	173-21-80-236.client.mchsi.com
173.21.80.244	A+PTR	173-21-80-244.client.mchsi.com
173.21.80.255	A	173-21-80-255.client.mchsi.com
173.21.82.16	A+PTR	173-21-82-16.client.mchsi.com
173.21.82.34	PTR	173-21-82-34.client.mchsi.com
173.21.82.43	A+PTR	173-21-82-43.client.mchsi.com
173.21.83.145	PTR	173-21-83-145.client.mchsi.com
173.21.83.145	A	mail.scottanderson.us
173.21.83.145	A	mail.thedemographic.com
173.21.84.26	A+PTR	173-21-84-26.client.mchsi.com
173.21.85.12	A	173-21-85-12.client.mchsi.com
173.21.85.130	A+PTR	173-21-85-130.client.mchsi.com
173.21.85.146	A+PTR	173-21-85-146.client.mchsi.com
173.21.85.156	A	173-21-85-156.client.mchsi.com
173.21.85.160	A+PTR	173-21-85-160.client.mchsi.com
173.21.85.210	A+PTR	173-21-85-210.client.mchsi.com
173.21.87.166	PTR	173-21-87-166.client.mchsi.com
173.21.87.202	A+PTR	173-21-87-202.client.mchsi.com
173.21.87.244	PTR	173-21-87-244.client.mchsi.com