Robtex

Up: 158.230.0.0/15
Can't show all results, try to descend to a more specific CIDR
Down left: 158.230.0.0/17
Down right: 158.230.128.0/17

IP	Type	Hostname
158.230.44.196	A+PTR	inmsweb.o2.com
158.230.100.73	A+PTR	ukdmzcsg.o2.com
158.230.100.75	A+PTR	ukcag.o2.com
158.230.100.101	A	dns0.btcellnet.net
158.230.100.102	A	cellgate.btcellnet.net
158.230.101.13	A	o365mail.o2.com
158.230.101.36	A	outlook.o2.com
158.230.101.53	A	lync.o2.com
158.230.101.116	A	cwa.o2.com
158.230.201.10	A	dmell-seg-03.o2.com
158.230.201.11	A	dmell-seg-04.o2.com