Robtex

Up: 66.210.56.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 66.210.56.0/23
Down right: 66.210.58.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
66.210.56.0	PTR	66-210-56-0.tuhsd.k12.az.us
66.210.57.11	A	wsip-66-210-57-11.ph.ph.cox.net
66.210.57.147	PTR	66-210-57-147.tuhsd.k12.az.us
66.210.57.148	PTR	66-210-57-148.tuhsd.k12.az.us
66.210.57.148	A	greenhearthappy.com
66.210.57.148	A	martialartstoolbox.com
66.210.57.149	PTR	66-210-57-149.tuhsd.k12.az.us
66.210.57.150	PTR	mtp-webwork-a.tuhsd.k12.az.us
66.210.59.101	PTR	mail2.blackboard.com
66.210.59.102	PTR	mail2.blackboard.com
66.210.59.149	PTR	wsip-66-210-59-149.ph.ph.cox.net
66.210.59.222	PTR	wsip-66-210-59-222.ph.ph.cox.net
66.210.59.243	PTR	wsip-66-210-59-243.ph.ph.cox.net