Robtex

Up: 194.121.0.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 194.121.4.0/23
Down right: 194.121.6.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
194.121.4.22	PTR	static.kpn.net
194.121.4.22	A	mail.ballegooyenmodes.com
194.121.5.218	PTR	static.kpn.net
194.121.5.218	A	fallback.s-bit.nl
194.121.7.26	PTR	mail2.bierens-advocaten.com
194.121.7.26	A	mail2.arpa-oa.nl
194.121.7.26	A	mail2.bierensgroup.it
194.121.7.27	PTR	static.kpn.net
194.121.7.42	PTR	static.kpn.net
194.121.7.42	A	mail.dulfer-intermediairs.nl
194.121.7.42	A	mail.uitzendburo-sintra.nl