Robtex

Up: 81.88.16.0/20
Can't show all results, try to descend to a more specific CIDR
Down left: 81.88.16.0/22
Down right: 81.88.20.0/22
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
81.88.16.1	PTR	r01-srv16.dus.de.tensteps.net
81.88.16.1	A	gw.core1.dus1.de.as31342.net
81.88.17.1	A+PTR	gw.core1.dus1.de.as31342.net
81.88.17.101	A	server1.yourwebstart.com
81.88.18.1	A+PTR	gw.core1.dus1.de.as31342.net
81.88.18.20	A	chartmailer.de
81.88.18.20	A	mail.boersen-magazin.com
81.88.18.20	A	fta-ltd.com
81.88.18.42	PTR	81.88.18.42.static.clanordns.net
81.88.18.42	A	rosaleks.de
81.88.18.42	A	mail.rosaleks.de
81.88.18.51	A	mail10.baite05.de
81.88.18.51	A	baite05.de
81.88.18.61	A	gemballa-investors.com
81.88.18.61	A	www.gemballa-investors.com
81.88.18.107	PTR	81.88.18.107.static.clanordns.net
81.88.18.194	PTR	web1.collin.pro
81.88.18.194	A	xn--wiike-ova.de
81.88.18.194	A	taxischeininfo.de
81.88.19.1	A+PTR	gw.core1.dus1.de.as31342.net
81.88.19.3	A+PTR	81.88.19.3.static.clanordns.net
81.88.19.3	A	mich-durstet.de
81.88.19.3	A	textlink.net
81.88.19.15	A	81.88.19.15.static.clanordns.net
81.88.19.23	A	81.88.19.23.static.clanordns.net
81.88.19.45	A	mail.chickenchecker.com
81.88.20.1	PTR	81.88.20.1.static.clanordns.net
81.88.20.1	A	gw.core1.dus1.de.as31342.net
81.88.20.251	PTR	81.88.20.251.static.clanordns.net
81.88.20.251	A	grafvonschwerin.de
81.88.20.251	A	*.grafvonschwerin.de
81.88.21.1	A	gw.core1.dus1.de.as31342.net
81.88.21.25	PTR	81.88.21.25.static.maltavpn.net
81.88.21.25	A	asmodis-vap.mb-net.net
81.88.21.31	A	dns1.maxhost.de
81.88.21.32	A	web7.i-line.net
81.88.21.32	A	b-smtp02.essen.uplink.i-line.net
81.88.21.34	A	i-line.net
81.88.21.34	A	81.88.21.34.static.clanordns.net
81.88.22.1	A+PTR	gw.core1.dus1.de.as31342.net
81.88.22.1	A	mail1.oliverstorck.de
81.88.22.1	A	mail1.jazzzy.de
81.88.22.6	A	81.88.22.6.static.clanordns.net
81.88.22.10	A+PTR	81.88.22.10.static.clanordns.net
81.88.22.66	A+PTR	server1.maschinist.org
81.88.22.66	A	mail.deutschtag.de
81.88.22.66	A	mail.mint-berlin.com
81.88.22.82	PTR	opub.de
81.88.22.82	A	mail.netz-funk.de
81.88.22.82	A	www.vaplab.de
81.88.22.83	PTR	opub.de
81.88.22.90	PTR	opub.de
81.88.22.90	A	rene.regelt.de
81.88.22.94	A	chat.jazzzy.de
81.88.22.98	PTR	braun.tk
81.88.22.98	A	mail.mycomicworld.com
81.88.22.98	A	unitedlabels.at
81.88.23.1	A+PTR	gw.core1.dus1.de.as31342.net
81.88.23.2	A	ns2.opub.de
81.88.23.2	A	ns2.oliverstorck.de
81.88.23.6	A	mail.braun.tk