Robtex

Up: 72.30.216.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 72.30.220.0/23
Down right: 72.30.222.0/23

IP	Type	Hostname
72.30.220.1	PTR	unknown-72-30-220-x.yahoo.com
72.30.220.28	PTR	unknown-72-30-220-x.yahoo.com
72.30.220.63	PTR	unknown-72-30-220-x.yahoo.com
72.30.220.68	PTR	unknown-72-30-220-x.yahoo.com
72.30.220.74	PTR	unknown-72-30-220-x.yahoo.com
72.30.220.90	PTR	unknown-72-30-220-x.yahoo.com
72.30.220.111	PTR	unknown-72-30-220-x.yahoo.com
72.30.220.137	PTR	unknown-72-30-220-x.yahoo.com
72.30.220.175	PTR	unknown-72-30-220-x.yahoo.com
72.30.220.190	PTR	unknown-72-30-220-x.yahoo.com
72.30.220.232	A	a1.dns.atz.yahoo.com
72.30.222.69	A	ha5.ge-4-1.bas-1-con.ac2.yahoo.com
72.30.222.76	A+PTR	ge-4-1.bas4-1-con.ac2.yahoo.com