Robtex

Up: 81.17.240.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 81.17.240.0/25
Down right: 81.17.240.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
81.17.240.0	PTR	240-0.colo.sta.blacknight.ie
81.17.240.1	PTR	rr01.bk1.39122.as
81.17.240.2	PTR	rr02.bk1.39122.as
81.17.240.3	PTR	edge-r01.bk1.39122.as
81.17.240.4	PTR	edge-r02.bk1.39122.as
81.17.240.5	PTR	dr-r01.bk1.39122.as
81.17.240.6	PTR	dr-r02.bk1.39122.as
81.17.240.7	PTR	240-7.colo.sta.blacknight.ie
81.17.240.8	PTR	240-8.colo.sta.blacknight.ie
81.17.240.9	PTR	240-9.colo.sta.blacknight.ie
81.17.240.10	PTR	240-10.colo.sta.blacknight.ie
81.17.240.11	PTR	240-11.colo.sta.blacknight.ie
81.17.240.12	PTR	240-12.colo.sta.blacknight.ie
81.17.240.13	PTR	240-13.colo.sta.blacknight.ie
81.17.240.14	PTR	acc-r01.bk1.39122.as
81.17.240.15	PTR	240-15.colo.sta.blacknight.ie
81.17.240.16	PTR	240-16.colo.sta.blacknight.ie
81.17.240.17	PTR	240-17.colo.sta.blacknight.ie
81.17.240.18	PTR	240-18.colo.sta.blacknight.ie
81.17.240.19	PTR	240-19.colo.sta.blacknight.ie
81.17.240.24	PTR	240-24.colo.sta.blacknight.ie
81.17.240.40	PTR	240-40.colo.sta.blacknight.ie
81.17.240.49	PTR	ge3-10.edge-r01.bk1.39122.as
81.17.240.54	PTR	ge0-0-0.acc-r01.bk1.39122.as
81.17.240.97	PTR	240-97.colo.sta.blacknight.ie
81.17.240.100	PTR	240-100.colo.sta.blacknight.ie
81.17.240.121	PTR	240-121.colo.sta.blacknight.ie
81.17.240.156	PTR	240-156.colo.sta.blacknight.ie
81.17.240.156	A	wap2.nameonhold.com
81.17.240.156	A	ns2.nameonhold.com
81.17.240.165	PTR	g0.core-r02.bk1.39122.as
81.17.240.186	PTR	acc-sw14.bk1.39122.as
81.17.240.194	A+PTR	dns1.blacknight.ie
81.17.240.195	A+PTR	dns2.blacknight.ie
81.17.240.197	PTR	240-197.colo.sta.blacknight.ie
81.17.240.198	PTR	240-198.colo.sta.blacknight.ie
81.17.240.199	PTR	240-199.colo.sta.blacknight.ie
81.17.240.199	A	www.cars.je
81.17.240.199	A	ring.ie
81.17.240.203	PTR	240-203.colo.sta.blacknight.ie
81.17.240.204	PTR	ns.blacknightsolutions.com
81.17.240.204	A	hybodus.blacknight.ie
81.17.240.204	A	ns1.webdream.ie
81.17.240.211	A+PTR	merlin.blacknight.ie
81.17.240.211	A	mail.blacknight.ie
81.17.240.212	A+PTR	support.blacknight.ie
81.17.240.212	A	support.blacknight.com
81.17.240.214	PTR	av-priv.blacknight.ie
81.17.240.214	A	mail.eternalseptember.com
81.17.240.214	A	www.eternalseptember.com
81.17.240.225	PTR	240-225.colo.sta.blacknight.ie
81.17.240.225	A	lucius.blacknight.ie
81.17.240.227	A	billing.blacknight.ie
81.17.240.229	A+PTR	db.blacknight.ie
81.17.240.230	A+PTR	xen1.blacknight.ie
81.17.240.230	A	lucan.blacknight.ie
81.17.240.231	PTR	uptime.blacknight.ie
81.17.240.231	A	magic.budgetdns.com
81.17.240.232	A	mailwatch.blacknight.ie
81.17.240.232	A	forward.budgetdns.com
81.17.240.252	PTR	240-252.colo.sta.blacknight.ie
81.17.240.255	PTR	240-255.colo.sta.blacknight.ie