Robtex

Up: 173.20.48.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 173.20.48.0/23
Down right: 173.20.50.0/23

IP	Type	Hostname
173.20.48.51	A+PTR	173-20-48-51.client.mchsi.com
173.20.48.135	A+PTR	173-20-48-135.client.mchsi.com
173.20.49.2	A+PTR	173-20-49-2.client.mchsi.com
173.20.49.10	A+PTR	173-20-49-10.client.mchsi.com
173.20.49.12	A+PTR	173-20-49-12.client.mchsi.com
173.20.49.13	A+PTR	173-20-49-13.client.mchsi.com
173.20.49.15	A+PTR	173-20-49-15.client.mchsi.com
173.20.49.21	A+PTR	173-20-49-21.client.mchsi.com
173.20.49.24	A+PTR	173-20-49-24.client.mchsi.com
173.20.49.34	A+PTR	173-20-49-34.client.mchsi.com
173.20.49.41	A+PTR	173-20-49-41.client.mchsi.com
173.20.49.43	A+PTR	173-20-49-43.client.mchsi.com
173.20.49.49	A+PTR	173-20-49-49.client.mchsi.com
173.20.49.59	A+PTR	173-20-49-59.client.mchsi.com
173.20.49.61	A+PTR	173-20-49-61.client.mchsi.com
173.20.49.62	A+PTR	173-20-49-62.client.mchsi.com
173.20.49.63	A+PTR	173-20-49-63.client.mchsi.com
173.20.49.74	A+PTR	173-20-49-74.client.mchsi.com
173.20.49.86	A+PTR	173-20-49-86.client.mchsi.com
173.20.49.87	A+PTR	173-20-49-87.client.mchsi.com
173.20.49.88	A+PTR	173-20-49-88.client.mchsi.com
173.20.49.94	A+PTR	173-20-49-94.client.mchsi.com
173.20.49.97	A+PTR	173-20-49-97.client.mchsi.com
173.20.49.99	A+PTR	173-20-49-99.client.mchsi.com
173.20.49.134	A+PTR	173-20-49-134.client.mchsi.com
173.20.49.139	A+PTR	173-20-49-139.client.mchsi.com
173.20.49.140	A+PTR	173-20-49-140.client.mchsi.com
173.20.49.149	A+PTR	173-20-49-149.client.mchsi.com
173.20.49.150	A+PTR	173-20-49-150.client.mchsi.com
173.20.49.152	A+PTR	173-20-49-152.client.mchsi.com
173.20.49.156	A+PTR	173-20-49-156.client.mchsi.com
173.20.49.160	A+PTR	173-20-49-160.client.mchsi.com
173.20.49.166	A+PTR	173-20-49-166.client.mchsi.com
173.20.49.184	A+PTR	173-20-49-184.client.mchsi.com
173.20.49.189	A+PTR	173-20-49-189.client.mchsi.com
173.20.49.190	A+PTR	173-20-49-190.client.mchsi.com
173.20.49.191	A+PTR	173-20-49-191.client.mchsi.com
173.20.49.192	A+PTR	173-20-49-192.client.mchsi.com
173.20.49.197	A+PTR	173-20-49-197.client.mchsi.com
173.20.49.201	A+PTR	173-20-49-201.client.mchsi.com
173.20.49.208	A+PTR	173-20-49-208.client.mchsi.com
173.20.49.209	A+PTR	173-20-49-209.client.mchsi.com
173.20.49.215	A+PTR	173-20-49-215.client.mchsi.com
173.20.49.219	A+PTR	173-20-49-219.client.mchsi.com
173.20.49.222	A+PTR	173-20-49-222.client.mchsi.com
173.20.49.223	A+PTR	173-20-49-223.client.mchsi.com
173.20.49.226	A+PTR	173-20-49-226.client.mchsi.com
173.20.49.230	A+PTR	173-20-49-230.client.mchsi.com
173.20.49.246	A+PTR	173-20-49-246.client.mchsi.com
173.20.49.250	A+PTR	173-20-49-250.client.mchsi.com
173.20.49.251	A+PTR	173-20-49-251.client.mchsi.com
173.20.49.254	A+PTR	173-20-49-254.client.mchsi.com
173.20.50.3	A+PTR	173-20-50-3.client.mchsi.com
173.20.50.152	PTR	173-20-50-152.client.mchsi.com
173.20.50.214	A+PTR	173-20-50-214.client.mchsi.com