Robtex

Up: 64.140.0.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 64.140.4.0/23
Down right: 64.140.6.0/23

IP	Type	Hostname
64.140.4.68	PTR	mail.rmsboulder.com
64.140.4.68	A	mail.team3stripes.com
64.140.4.93	PTR	public.cworxs.com
64.140.5.3	PTR	dns4.ike.com
64.140.5.194	A	mail.lacunaresearch.com
64.140.5.194	A	64-140-5-194.icg.net
64.140.5.198	A+PTR	64-140-5-198.icg.net
64.140.5.198	A	bluesemiconductors.com
64.140.5.199	A	64-140-5-199.icg.net
64.140.5.205	PTR	64-140-5-205.icg.net
64.140.6.194	A	mail.lrflegal.com
64.140.7.157	A	t1-3-1-0-1-28.edge1.denver1.level3.net