Robtex

Up: 81.4.112.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 81.4.116.0/23
Down right: 81.4.118.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
81.4.116.5	PTR	ip-space.by.proserve.nl
81.4.116.18	A	mail.airview.nl
81.4.116.37	A+PTR	ns3.lucrasoft.nl
81.4.116.43	A+PTR	sf-mx.lucrasoft.nl
81.4.116.43	A	sf-mx.opendoorzorg.nl
81.4.116.43	A	spamfilter.lucrasoft.nl
81.4.116.60	PTR	ip-space.by.proserve.nl
81.4.116.60	A	epspagid.nl
81.4.116.60	A	epsautomotive.nl
81.4.116.64	PTR	ip-space.by.proserve.nl
81.4.116.98	A	mail.apposy.com
81.4.116.104	PTR	ip-space.by.proserve.nl
81.4.116.104	A	mail.bhsbarendrecht.nl
81.4.116.104	A	mail.poelbouw.nl
81.4.116.105	PTR	vs03.dalosy.com
81.4.116.107	PTR	ip-space.by.proserve.nl
81.4.116.116	A	mail.ontwikkelingproeftuin.nl
81.4.116.116	A	mail.cornelisland.nl
81.4.116.117	PTR	ip-space.by.proserve.nl
81.4.116.117	A	mail.logilabel.be
81.4.116.117	A	mail.zebrasupplies.de
81.4.116.118	PTR	ip-space.by.proserve.nl
81.4.116.119	PTR	ip-space.by.proserve.nl
81.4.116.131	A	webmail.itpartner.nl
81.4.116.132	PTR	ip-space.by.proserve.nl
81.4.116.133	A	smtp2.itpartner.nl
81.4.116.144	PTR	ip-space.by.proserve.nl
81.4.116.150	PTR	ip-space.by.proserve.nl
81.4.116.150	A	mail.smitmode.nl
81.4.116.154	PTR	ip-space.by.proserve.nl
81.4.116.154	A	smeerpoets.com
81.4.116.154	A	truckdoc.nl
81.4.116.186	PTR	ip-space.by.proserve.nl
81.4.117.2	PTR	ip-space.by.proserve.nl
81.4.117.2	A	mail.uradius.com
81.4.117.2	A	hia.wendrich.nl
81.4.117.25	PTR	ip-space.by.proserve.nl
81.4.117.26	PTR	ip-space.by.proserve.nl
81.4.117.26	A	mail2.phydis.nl
81.4.117.26	A	mail.kbs-ict.nl
81.4.117.50	A	mail.contenzo.nl
81.4.117.50	A	mail.prmservice.nl
81.4.117.51	PTR	ip-space.by.proserve.nl
81.4.117.51	A	contenzo.info
81.4.117.51	A	rastereditsoftware.com
81.4.118.55	PTR	ip-space.by.proserve.nl
81.4.118.255	PTR	ip-space.by.proserve.nl
81.4.119.58	PTR	ip-space.by.proserve.nl
81.4.119.220	PTR	ip-space.by.proserve.nl