Robtex

Up: 194.121.104.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 194.121.104.0/23
Down right: 194.121.106.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
194.121.104.0	A+PTR	net-local.ilk.de
194.121.104.8	A+PTR	unassigned-8.104.121.194.in-addr.arpa
194.121.104.8	A	smtp.ilk.net
194.121.104.8	A	smtp1.ilk.net
194.121.104.11	PTR	unassigned
194.121.104.47	A+PTR	unassigned-47.104.121.194.in-addr.arpa
194.121.104.78	PTR	unassigned
194.121.104.92	A+PTR	unassigned-92.104.121.194.in-addr.arpa
194.121.104.178	A+PTR	unassigned-178.104.121.194.in-addr.arpa