Robtex

Up: 91.201.16.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 91.201.20.0/23
Down right: 91.201.22.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
91.201.20.2	A	billing.alfatelecom.cz
91.201.20.10	A	hosting.alfatelecom.cz
91.201.20.20	A	mera.alfatelecom.cz
91.201.20.21	A	a2billing.alfatelecom.cz
91.201.20.22	A+PTR	pdu1.alfatelecom.cz
91.201.20.23	A	pdu2.alfatelecom.cz
91.201.20.30	PTR	rdns.revhost.net
91.201.20.30	A	ns2.alfatelecom.cz
91.201.20.33	A	kvm.alfatelecom.cz
91.201.20.34	A	newbilling.alfatelecom.cz
91.201.20.61	A	cs.alfatelecom.cz
91.201.20.248	A	mail.alfatelecom.cz
91.201.20.248	A	mail.ipaddr.cz
91.201.21.21	A+PTR	ns1.alfatelecom.cz
91.201.21.42	A+PTR	ns3.alfatelecom.cz
91.201.21.46	A	testvoiproutes.com
91.201.21.46	A	testvoiproutes.net
91.201.21.54	A	mail.grotor.com
91.201.21.54	A	grotor.ru
91.201.21.61	A	ipaddr.cz
91.201.21.61	A	www.alfatelecom.cz
91.201.21.61	A	alfatelecom.cz
91.201.21.66	PTR	mail.flamesgroup.com
91.201.21.132	PTR	ns0.ipxp.net
91.201.21.132	A	ns0.ipxp.eu
91.201.21.137	PTR	ipxp.net
91.201.21.150	A	ipxp.net
91.201.21.150	A	new.ipxp.net
91.201.21.150	A	ipxp.cz
91.201.21.162	A	mail.serverel.com
91.201.21.162	A	ns.sgmanaged.com
91.201.21.162	A	clients.serverel.com
91.201.21.166	PTR	clients.serverel.com
91.201.21.177	PTR	wtelecom.net
91.201.21.177	A	beast.wtelecom.net
91.201.21.177	A	sgphone.net
91.201.21.178	PTR	ns.apex.dp.ua
91.201.21.179	PTR	s3.ns.dp.ua
91.201.22.44	A	mail.cool-it-one.cz
91.201.22.44	A	mail.itprojekt.eu
91.201.22.45	A	cloud2air.cz
91.201.22.45	A	cool-it-one.cz
91.201.22.58	A	mail.prodesi.cz
91.201.22.67	A+PTR	mail.sfw.cz
91.201.22.67	A	ms.sfw.cz
91.201.22.137	A	mail.lbautomobile.cz
91.201.22.137	A	mail.lbautomobile.eu
91.201.22.156	A+PTR	remote.tkf.cz
91.201.22.156	A	mail2.tents.cz
91.201.22.156	A	mail.tkf.cz
91.201.22.162	A	mail.walco.cz
91.201.22.228	A	simon-mnichovice.cz
91.201.23.30	A	mail.e-vokzal.eu
91.201.23.36	A	out.dh.cz
91.201.23.37	A	posta.aerotrade.cz
91.201.23.46	A+PTR	jamie.vrana-pelikan.cz
91.201.23.46	A	brana.vrana-pelikan.cz
91.201.23.92	A+PTR	mail.servisproservisy.eu
91.201.23.92	A	mail.nadviktorkou.cz
91.201.23.92	A	nadviktorkou.cz
91.201.23.122	A	kancelar.vitakova.cz
91.201.23.122	A	vitakova.cz
91.201.23.195	A	router1.con4pas.cz