Robtex

Up: 217.12.15.0/24
Can't show all results, try to descend to a more specific CIDR
Down left: 217.12.15.128/26
Down right: 217.12.15.192/26
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
217.12.15.134	PTR	unknown-217-12-15-x.yahoo.com
217.12.15.139	PTR	unknown-217-12-15-x.yahoo.com
217.12.15.140	PTR	140.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.141	PTR	141.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.142	PTR	142.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.143	PTR	143.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.144	PTR	unknown-217-12-15-x.yahoo.com
217.12.15.146	PTR	unknown-217-12-15-x.yahoo.com
217.12.15.147	PTR	unknown.yahoo.com
217.12.15.148	PTR	redis-192-30.mqengine.media.ir2.yahoo.com
217.12.15.149	PTR	redis-192-29.mqengine.media.ir2.yahoo.com
217.12.15.150	PTR	redis-192-28.mqengine.media.ir2.yahoo.com
217.12.15.152	A+PTR	152.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.152	A	ats.apple.yql.vip.ir2.yahoo.com
217.12.15.175	PTR	e552472.ostk.bm2.prod.ir2.yahoo.com
217.12.15.176	A+PTR	dev5-vm1.maktoob.corp.ukl.yahoo.com
217.12.15.180	PTR	180.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.181	PTR	181.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.182	PTR	e552457.ostk.bm2.prod.ir2.yahoo.com
217.12.15.184	PTR	184.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.185	PTR	185.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.187	PTR	187.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.189	A+PTR	l52.member.ir2.yahoo.com
217.12.15.191	PTR	191.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.193	PTR	e552462.ostk.bm2.prod.ir2.yahoo.com
217.12.15.194	A+PTR	l54.member.ir2.yahoo.com
217.12.15.197	PTR	197.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.199	PTR	unknown-217-12-15-x.yahoo.com
217.12.15.200	PTR	200.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.204	PTR	204.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.205	PTR	205.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.206	PTR	unknown-217-12-15-x.yahoo.com
217.12.15.208	PTR	208.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.209	PTR	209.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.210	PTR	e552474.ostk.bm2.prod.ir2.yahoo.com
217.12.15.211	A	businesstest.maktoob.com
217.12.15.212	PTR	212.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.213	PTR	213.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.214	PTR	unknown-217-12-15-x.yahoo.com
217.12.15.215	PTR	215.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.218	PTR	e552464.ostk.bm2.prod.ir2.yahoo.com
217.12.15.220	PTR	3000606.ostk.bm2.prod.ir2.yahoo.com
217.12.15.221	PTR	unknown-217-12-15-x.yahoo.com
217.12.15.223	PTR	unknown-217-12-15-x.yahoo.com
217.12.15.225	PTR	unknown-217-12-15-x.yahoo.com
217.12.15.228	PTR	228.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.229	PTR	229.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.234	PTR	valhalla-j4.ops.corp.ukl.yahoo.com
217.12.15.236	PTR	20003457.ostk.bm2.prod.ir2.yahoo.com
217.12.15.238	PTR	20003451.ostk.bm2.prod.ir2.yahoo.com
217.12.15.249	PTR	249.15.12.217.aprez.ostk.prod.ir2.yahoo.com
217.12.15.250	PTR	unknown-217-12-15-x.yahoo.com
217.12.15.251	PTR	unknown-217-12-15-x.yahoo.com
217.12.15.253	A+PTR	ws1.yoscs.vip.ir2.yahoo.com
217.12.15.253	A	accountlink.yahoo.com
217.12.15.253	A	accountlink.www.yossocial.g01.yahoodns.net
217.12.15.255	PTR	unknown-217-12-15-x.yahoo.com