Robtex

Up: 193.228.72.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 193.228.72.0/23
Down right: 193.228.74.0/23

IP	Type	Hostname
193.228.72.33	A+PTR	mail.inviteinfo.com
193.228.72.33	A	server1.inviteinfo.com
193.228.72.55	A	stv1.hotprimal.com
193.228.72.113	A	server1.helloaffair.com
193.228.72.113	A	helloaffair.com
193.228.72.141	A	mail.hotprimal.com
193.228.72.141	A	ns1.hotprimal.com
193.228.72.141	A	hotprimal.com
193.228.72.142	PTR	stv1.hotprimal.com
193.228.72.142	A	ns2.hotprimal.com
193.228.73.81	A+PTR	mail.playaffair.com
193.228.73.81	A	server1.playaffair.com
193.228.74.193	A+PTR	mail.fidelityfun.com
193.228.74.193	A	server1.fidelityfun.com
193.228.75.33	A+PTR	mail.naughtyalert.com
193.228.75.33	A	server1.naughtyalert.com
193.228.75.125	A	server1.desiretap.com
193.228.75.129	A+PTR	mail.sendcute.com
193.228.75.129	A	server1.sendcute.com