Robtex

Up: 216.244.16.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 216.244.20.0/23
Down right: 216.244.22.0/23

IP	Type	Hostname
216.244.20.38	A+PTR	user-3cf8516.dsl.mindspring.com
216.244.20.157	A+PTR	user-3cf854t.dsl.mindspring.com
216.244.20.205	A+PTR	user-3cf856d.dsl.mindspring.com
216.244.21.16	A+PTR	user-3cf858g.dsl.mindspring.com
216.244.21.56	A+PTR	user-3cf859o.dsl.mindspring.com
216.244.21.60	A+PTR	user-3cf859s.dsl.mindspring.com
216.244.21.106	A	user-3cf85ba.dsl.mindspring.com
216.244.22.123	A+PTR	user-3cf85jr.dsl.mindspring.com
216.244.22.165	A+PTR	user-3cf85l5.dsl.mindspring.com
216.244.22.173	A+PTR	user-3cf85ld.dsl.mindspring.com
216.244.22.206	A+PTR	user-3cf85me.dsl.mindspring.com
216.244.22.253	A+PTR	user-3cf85nt.dsl.mindspring.com
216.244.23.57	A+PTR	user-3cf85pp.dsl.mindspring.com
216.244.23.139	A+PTR	user-3cf85sb.dsl.mindspring.com
216.244.23.162	A+PTR	user-3cf85t2.dsl.mindspring.com
216.244.23.193	A+PTR	user-3cf85u1.dsl.mindspring.com