Robtex

Up: 66.17.64.0/19
Can't show all results, try to descend to a more specific CIDR
Down left: 66.17.64.0/21
Down right: 66.17.72.0/21
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
66.17.64.0	PTR	h-66-17-64-0.noclli.covad.net
66.17.64.99	PTR	h-66-17-64-99.noclli.covad.net
66.17.67.66	PTR	h-66-17-67-66.noclli.covad.net
66.17.72.243	PTR	h-66-17-72-243.noclli.covad.net
66.17.72.243	A	beta.cnar.org
66.17.72.243	A	www.cnar.org
66.17.73.34	PTR	h-66-17-73-34.noclli.covad.net
66.17.73.226	PTR	h-66-17-73-226.noclli.covad.net
66.17.74.49	PTR	h-66-17-74-49.noclli.covad.net
66.17.76.1	PTR	h-66-17-76-1.noclli.covad.net
66.17.76.51	PTR	h-66-17-76-51.noclli.covad.net
66.17.78.1	PTR	h-66-17-78-1.noclli.covad.net
66.17.78.32	PTR	h-66-17-78-32.noclli.covad.net
66.17.78.33	PTR	h-66-17-78-33.noclli.covad.net
66.17.78.34	PTR	h-66-17-78-34.noclli.covad.net
66.17.78.51	PTR	h-66-17-78-51.noclli.covad.net
66.17.78.64	PTR	h-66-17-78-64.noclli.covad.net
66.17.78.66	PTR	h-66-17-78-66.noclli.covad.net
66.17.78.81	PTR	h-66-17-78-81.noclli.covad.net
66.17.78.114	PTR	h-66-17-78-114.noclli.covad.net
66.17.78.131	PTR	h-66-17-78-131.noclli.covad.net
66.17.78.176	PTR	h-66-17-78-176.noclli.covad.net
66.17.78.208	PTR	h-66-17-78-208.noclli.covad.net
66.17.78.210	PTR	h-66-17-78-210.noclli.covad.net
66.17.78.227	PTR	h-66-17-78-227.noclli.covad.net
66.17.79.48	PTR	h-66-17-79-48.noclli.covad.net
66.17.79.67	PTR	h-66-17-79-67.noclli.covad.net
66.17.79.81	PTR	smtp.overtone.com
66.17.79.97	PTR	h-66-17-79-97.noclli.covad.net
66.17.79.98	PTR	h-66-17-79-98.noclli.covad.net
66.17.79.112	PTR	h-66-17-79-112.noclli.covad.net
66.17.79.114	PTR	h-66-17-79-114.noclli.covad.net
66.17.79.129	PTR	h-66-17-79-129.noclli.covad.net
66.17.79.138	A	mail.cosmeticeyedoc.com
66.17.79.144	PTR	h-66-17-79-144.noclli.covad.net
66.17.79.147	PTR	h-66-17-79-147.noclli.covad.net
66.17.79.194	PTR	mail.cambriabike.com
66.17.79.226	PTR	h-66-17-79-226.noclli.covad.net
66.17.79.242	PTR	h-66-17-79-242.noclli.covad.net