Robtex

Up: 81.200.64.0/19
Can't show all results, try to descend to a more specific CIDR
Down left: 81.200.64.0/21
Down right: 81.200.72.0/21
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
81.200.64.50	PTR	advancedsearch.virginmedia.com
81.200.64.50	A	mx.wgtsport.com
81.200.64.50	A	paradislondon.co.uk
81.200.64.51	PTR	advancedsearch2.virginmedia.com
81.200.64.65	A+PTR	auth4.skyebynominum.com
81.200.64.65	A	zq706kj54lte0v3algp3dkkoegevg4odsiq0dm9f5u3og0l0sj94qpog.skyedns.net
81.200.64.65	A	zq706kj54lte0v3algp3dkkoegevg4odsiq0dm9f5u3og0l0sj94qpog.skyedns.com
81.200.64.70	A	res2.skyedns.com
81.200.64.81	PTR	old-shell-ng.nominum.com
81.200.64.134	A	quarto.nominum.com
81.200.64.144	A	folio.nominum.com
81.200.64.160	PTR	g2lf.skyebynominum.com
81.200.64.180	A	youngbusinesstalents.mx
81.200.64.180	A	dnssearch.jazztel.com
81.200.64.183	A	dnssearch.ono.es
81.200.64.183	A	baloncestovillaviciosadeodon.com
81.200.65.81	PTR	pao-nx-v01.skyebynominum.com
81.200.65.82	PTR	verizon.skyebynominum.com
81.200.65.84	PTR	search.skyebynominum.com
81.200.66.1	PTR	lhr-ui01.web.skyebynominum.com
81.200.66.2	PTR	lhr-ui02.web.skyebynominum.com
81.200.66.3	PTR	lhr-ui03.web.skyebynominum.com
81.200.66.4	A	c2385.nominum.com
81.200.66.24	A+PTR	lhr-sorsdb.bo.skyebynominum.com
81.200.66.28	PTR	lhr-sorsdb01.bo.skyebynominum.com
81.200.66.29	A+PTR	lhr-sorsdb02.bo.skyebynominum.com
81.200.66.30	PTR	lhr-sorsdb03.bo.skyebynominum.com
81.200.66.32	PTR	lhr-site02.web.skyebynominum.com
81.200.66.33	PTR	lhr-site03.web.skyebynominum.com
81.200.66.40	A+PTR	lhr-sors.web.skyebynominum.com
81.200.66.49	PTR	lhr-srch09.web.skyebynominum.com
81.200.66.83	PTR	lhr-iview.ngn.nominum.com
81.200.66.105	PTR	res15.skyedns.com
81.200.66.114	PTR	lhr-cnslb02.dns.skyebynominum.com
81.200.66.115	PTR	lhr-cnslb03.dns.skyebynominum.com
81.200.66.121	PTR	lhr-anslb01.dns.skyebynominum.com
81.200.66.122	A	rir-1.eng-lab.nominum.com
81.200.66.129	PTR	lhr-cnsac01.dns.skyebynominum.com
81.200.66.137	PTR	lhr-ansac01.dns.skyebynominum.com
81.200.66.138	PTR	lhr-cnsac02.dns.skyebynominum.com
81.200.66.175	PTR	lhr-prv01.bo.skyebynominum.com
81.200.66.176	PTR	lhr-prv02.bo.skyebynominum.com
81.200.66.177	PTR	lhr-prv03.bo.skyebynominum.com
81.200.66.180	PTR	lhr-dmgt01.bo.skyebynominum.com
81.200.66.181	PTR	lhr-dmgt02.bo.skyebynominum.com
81.200.66.193	PTR	lhr-ops01.mgmt.skyebynominum.com
81.200.66.194	PTR	lhr-ops02.mgmt.skyebynominum.com
81.200.66.195	PTR	lhr-ops03.mgmt.skyebynominum.com
81.200.66.254	A+PTR	lhr-rtr01.mgmt.skyebynominum.com
81.200.66.255	PTR	lhr-rtr02.mgmt.skyebynominum.com
81.200.67.1	PTR	fra-ui01.web.skyebynominum.com
81.200.67.2	PTR	fra-ui02.web.skyebynominum.com
81.200.67.3	PTR	fra-ui03.web.skyebynominum.com
81.200.67.17	PTR	fra-nxr01.web.skyebynominum.com
81.200.67.24	A+PTR	fra-sorsdb.bo.skyebynominum.com
81.200.67.28	PTR	fra-sorsdb01.bo.skyebynominum.com
81.200.67.33	A+PTR	fra-site03.web.skyebynominum.com
81.200.67.34	PTR	fra-site04.web.skyebynominum.com
81.200.67.40	PTR	fra-sors.web.skeybynominum.com
81.200.67.45	A	fra-srch05.web.skyebynominum.com
81.200.67.49	PTR	fra-srch09.web.skyebynominum.com
81.200.67.53	PTR	fra-vanlb01.dns.skyebynominum.com
81.200.67.54	PTR	fra-vanlb02.dns.skyebynominum.com
81.200.67.85	PTR	search-eu.skyebynominum.com
81.200.67.105	PTR	res16.skyedns.com
81.200.67.114	PTR	fra-cnslb02.dns.skyebynominum.com
81.200.67.121	A+PTR	fra-anslb01.dns.skyebynominum.com
81.200.67.122	A	fra-anslb02.dns.skyebynominum.com
81.200.67.129	PTR	fra-cnsac01.dns.skyebynominum.com
81.200.67.130	PTR	fra-cnsac02.dns.skyebynominum.com
81.200.67.137	A+PTR	fra-ansac01.dns.skyebynominum.com
81.200.67.167	A+PTR	fra-cntr01.dns.skyebynominum.com
81.200.67.168	PTR	fra-cntr02.dns.skyebynominum.com
81.200.67.176	PTR	fra-prv02.bo.skyebynominum.com
81.200.67.177	PTR	fra-prv03.bo.skyebynominum.com
81.200.67.180	PTR	fra-dmgt01.bo.skyebynominum.com
81.200.67.181	PTR	fra-dmgt02.bo.skyebynominum.com
81.200.67.185	A	fra-ansm01.dns.skyebynominum.com
81.200.67.194	A+PTR	fra-ops02.mgmt.skyebynominum.com
81.200.67.195	PTR	fra-ops03.mgmt.skyebynominum.com
81.200.67.254	PTR	fra-rtr01.mgmt.skyebynominum.com
81.200.67.255	A+PTR	fra-rtr02.mgmt.skyebynominum.com
81.200.68.201	A	dnstest.nominum.com
81.200.68.213	A	webbox.nominum.com
81.200.68.228	A	spamhaus-test-1.nominum.com
81.200.68.229	A	spamhaus-test-2.nominum.com
81.200.68.230	A	trend-test-1.nominum.com
81.200.68.231	A	trend-test-2.nominum.com
81.200.69.35	A	ns6.nominum.eu
81.200.69.153	A	ns9.nominum.eu