Robtex

Up: 216.136.128.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 216.136.128.0/23
Down right: 216.136.130.0/23

IP	Type	Hostname
216.136.128.0	PTR	unknown-216-136-128-x.yahoo.com
216.136.128.23	A+PTR	mta-vm1.mail.yahoo.com
216.136.128.54	A	mta402.mail.yahoo.com
216.136.128.58	A+PTR	mx1d.mail.yahoo.com
216.136.128.59	A+PTR	mx1d.mail.yahoo.com
216.136.128.60	A+PTR	mx1d.mail.yahoo.com
216.136.128.61	A+PTR	mx1d.mail.yahoo.com
216.136.128.62	A+PTR	mx1d.mail.yahoo.com
216.136.128.63	A+PTR	mx2a.mail.yahoo.com
216.136.128.64	A+PTR	mx2a.mail.yahoo.com
216.136.128.65	A+PTR	mx2a.mail.yahoo.com
216.136.128.101	A	web14502.mail.yahoo.com
216.136.128.102	A+PTR	web14503.mail.yahoo.com
216.136.128.109	A+PTR	tts24.phone.yahoo.com
216.136.128.134	A	mta520.mail.yahoo.com
216.136.128.148	A	mta528.mail.yahoo.com
216.136.128.151	A+PTR	vc2.phone.yahoo.com
216.136.128.155	A	vc6.phone.yahoo.com
216.136.128.170	A+PTR	web9008.mail.yahoo.com
216.136.128.172	A	web9010.mail.yahoo.com
216.136.128.249	A	notify24.yahoo.com
216.136.128.250	A	notify25.yahoo.com
216.136.129.5	A+PTR	mta-v22.mail.yahoo.com
216.136.129.12	A	mta-v17.mail.yahoo.com
216.136.129.13	A	mta-v16.mail.yahoo.com
216.136.129.14	A+PTR	mta-v15.mail.yahoo.com
216.136.129.15	A+PTR	mta-v14.mail.yahoo.com
216.136.129.16	A+PTR	mta-v11.mail.yahoo.com
216.136.129.18	A+PTR	mta-v13.mail.yahoo.com
216.136.129.44	A	people9201.mail.yahoo.com
216.136.129.77	A+PTR	mx1d.mail.yahoo.com
216.136.129.141	A	web21305.mail.yahoo.com
216.136.129.190	A	web21304.mail.yahoo.com
216.136.129.203	A	mta531.mail.yahoo.com
216.136.129.229	A	cas10.phone.yahoo.com
216.136.130.14	A+PTR	mta504.mail.yahoo.com
216.136.130.17	A+PTR	mta507.mail.yahoo.com
216.136.130.26	A	mta510.mail.yahoo.com
216.136.130.27	A	mta533.mail.yahoo.com
216.136.130.105	A+PTR	mx2a.mail.yahoo.com
216.136.130.106	A+PTR	mx2a.mail.yahoo.com
216.136.130.107	A+PTR	mx2a.mail.yahoo.com
216.136.130.108	PTR	mta309.mail.yahoo.com
216.136.130.108	A	mx2a.mail.yahoo.com
216.136.130.109	A+PTR	mta310.mail.yahoo.com
216.136.130.109	A	mx2a.mail.yahoo.com
216.136.130.183	PTR	unknown-216-136-130-x.yahoo.com
216.136.130.183	A	mail.drmarkblue.com
216.136.130.194	PTR	unknown-216-136-130-x.yahoo.com
216.136.130.194	A	mail.drmarkblue.com
216.136.130.199	PTR	mta491.mail.yahoo.com
216.136.130.199	A	mx1i.mail.yahoo.com
216.136.130.236	A+PTR	ypolls.yahoo.com
216.136.131.5	A	pc5.phone.yahoo.com
216.136.131.15	A	mx1i.mail.yahoo.com
216.136.131.21	A	mta539.mail.yahoo.com
216.136.131.22	A	mta540.mail.yahoo.com
216.136.131.23	A	mta541.mail.yahoo.com
216.136.131.24	A	mta542.mail.yahoo.com
216.136.131.26	A+PTR	mta544.mail.yahoo.com
216.136.131.26	A	mx1i.mail.yahoo.com
216.136.131.27	A	mx1i.mail.yahoo.com
216.136.131.28	A	mx1i.mail.yahoo.com
216.136.131.29	A	mx1i.mail.yahoo.com
216.136.131.31	A	mx1i.mail.yahoo.com
216.136.131.31	A	mta548.mail.yahoo.com
216.136.131.32	A+PTR	mta549.mail.yahoo.com
216.136.131.32	A	mx1i.mail.yahoo.com
216.136.131.73	A+PTR	ms2.oa.yahoo.com
216.136.131.74	A+PTR	p2.vision.yahoo.com
216.136.131.84	A+PTR	t1.class.yahoo.com
216.136.131.108	A	qum1b.msg.yahoo.com
216.136.131.241	PTR	unknown-216-136-131-x.yahoo.com
216.136.131.253	A	mta514.mail.yahoo.com
216.136.131.254	A	mta515.mail.yahoo.com