Robtex

Up: 66.231.20.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 66.231.21.0/25
Down right: 66.231.21.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
66.231.21.0	A+PTR	0.21.231.66.unassigned.sdncommunications.com
66.231.21.57	A+PTR	57.21.231.66.unassigned.sdncommunications.com
66.231.21.57	A	ipv4-c002-fsd002-sdn-isp.1.oca.nflxvideo.net
66.231.21.57	A	occ-0-738-1239.1.nflxso.net
66.231.21.62	A	ipv4-c003-fsd001-sdn-isp.1.oca.nflxvideo.net
66.231.21.66	A+PTR	66.21.231.66.unassigned.sdncommunications.com
66.231.21.66	A	occ-0-711-1239.1.nflxso.net
66.231.21.66	A	occ-1-711-1239.1.nflxso.net
66.231.21.82	A+PTR	82.21.231.66.unassigned.sdncommunications.com
66.231.21.98	A+PTR	98.21.231.66.unassigned.sdncommunications.com
66.231.21.114	PTR	114.21.231.66.unassigned.sdncommunications.com
66.231.21.114	A	occ-0-888-1239.1.nflxso.net
66.231.21.114	A	occ-1-888-1239.1.nflxso.net
66.231.21.201	PTR	hu0-2-1-0.sxflsdch38r.bntpsdae02r.sdnet.net