Robtex

Up: 206.17.16.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 206.17.20.0/23
Down right: 206.17.22.0/23

IP	Type	Hostname
206.17.20.9	A+PTR	ns2.attcompute.com
206.17.20.11	A+PTR	ns1.attcompute.com
206.17.20.11	A	ns3.attcompute.com
206.17.20.14	PTR	mvc.att
206.17.20.46	PTR	unused.att
206.17.20.49	PTR	unused.att
206.17.20.62	PTR	unused.att
206.17.20.75	PTR	unused.att
206.17.20.113	PTR	unused.att
206.17.20.116	PTR	unused.att
206.17.20.121	PTR	unused.att
206.17.20.186	PTR	unused.att
206.17.20.186	A	enet.hlpusd.k12.ca.us
206.17.20.192	PTR	unused.att
206.17.20.210	PTR	unused.att
206.17.21.17	PTR	unused.att
206.17.21.49	PTR	unused.att
206.17.21.67	PTR	unused.att
206.17.21.111	PTR	unused.att
206.17.21.170	PTR	unused.att
206.17.21.229	PTR	unused.att
206.17.21.232	PTR	unused.att
206.17.21.247	PTR	unused.att
206.17.22.1	PTR	unused.att
206.17.22.27	PTR	unused.att
206.17.22.64	PTR	unused.att
206.17.22.68	PTR	unused.att
206.17.22.97	PTR	unused.att
206.17.22.127	PTR	unused.att
206.17.22.131	PTR	unused.att
206.17.22.139	PTR	unused.att
206.17.23.44	PTR	unused.att
206.17.23.53	PTR	unused.att
206.17.23.122	PTR	unused.att
206.17.23.136	PTR	unused.att
206.17.23.148	PTR	unused.att
206.17.23.161	PTR	unused.att
206.17.23.213	PTR	unused.att
206.17.23.239	PTR	unused.att