Robtex

Up: 66.81.240.0/20
Can't show all results, try to descend to a more specific CIDR
Down left: 66.81.248.0/22
Down right: 66.81.252.0/22

IP	Type	Hostname
66.81.248.9	PTR	o1-66-81-248-9.static.o1.com
66.81.248.16	A+PTR	global-66-81-248-16.dialup.o1.com
66.81.248.146	A	global-66-81-248-146.dialup.o1.com
66.81.249.168	PTR	global-66-81-249-168.dialup.o1.com
66.81.249.226	PTR	global-66-81-249-226.dialup.o1.com
66.81.249.232	PTR	global-66-81-249-232.dialup.o1.com
66.81.249.249	A+PTR	global-66-81-249-249.dialup.o1.com
66.81.250.53	A	global-66-81-250-53.dialup.o1.com
66.81.250.65	A	global-66-81-250-65.dialup.o1.com
66.81.250.79	A	global-66-81-250-79.dialup.o1.com
66.81.250.136	PTR	global-66-81-250-136.dialup.o1.com
66.81.251.95	A	global-66-81-251-95.dialup.o1.com
66.81.251.96	A	global-66-81-251-96.dialup.o1.com
66.81.251.123	PTR	global-66-81-251-123.dialup.o1.com
66.81.252.41	PTR	global-66-81-252-41.dialup.o1.com
66.81.253.2	PTR	global-66-81-253-2.dialup.o1.com
66.81.253.70	A	global-66-81-253-70.dialup.o1.com
66.81.253.75	A+PTR	global-66-81-253-75.dialup.o1.com
66.81.253.128	A	global-66-81-253-128.dialup.o1.com
66.81.253.160	A+PTR	global-66-81-253-160.dialup.o1.com
66.81.255.150	A	global-66-81-255-150.dialup.o1.com