Robtex

Up: 64.22.160.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 64.22.160.0/25
Down right: 64.22.160.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
64.22.160.1	A	cit1.citadelgroup.com
64.22.160.10	A	citadelgroup.info
64.22.160.11	A	mx1.rmvcommunications.com
64.22.160.12	A	mx2.rmvcommunications.com
64.22.160.13	A+PTR	mx1.citadelgroup.com
64.22.160.13	A	mx1.citadel.com
64.22.160.13	A	mx1.citidelgroup.com
64.22.160.14	A+PTR	mx2.citadelgroup.com
64.22.160.14	A	mx2.citidelgroup.com
64.22.160.14	A	mx2.citadel.com
64.22.160.16	A+PTR	remote-access.citadelgroup.com
64.22.160.16	A	login.citadelgroup.com
64.22.160.17	A	cestest.citadelgroup.com
64.22.160.21	A+PTR	mx4.citadelgroup.com
64.22.160.28	A	e-glue.co.uk
64.22.160.28	A	e-glue.us
64.22.160.28	A	pioneerpathcap.com
64.22.160.31	A	mail1.citadelgroup.mobi
64.22.160.32	A	sys1.citadelgroup.com
64.22.160.35	A+PTR	kcgvpn.citadelgroup.com
64.22.160.35	A+PTR	vacc.citinv.com
64.22.160.36	A+PTR	ftp.citadel.com
64.22.160.50	A+PTR	ns5.citadelgroup.info
64.22.160.50	A	ns5.citadelgroup.com
64.22.160.70	A	img.citadelgroup.com
64.22.160.79	A	reach.citadel.com
64.22.160.97	A	seg-dbn.citadel.com
64.22.160.102	A+PTR	mx5.citadelgroup.com
64.22.160.102	A	mx5.citadel.com
64.22.160.103	A	mx6.citadel.com
64.22.160.108	A	login.citadelgroup.com
64.22.160.108	A	remote-access.citadelgroup.com
64.22.160.144	A	mti1.citadelgroup.com
64.22.160.144	A	mx1.citadelgroup.info
64.22.160.145	A+PTR	mx2.citadelgroup.info
64.22.160.145	A	mto1.citadelgroup.com
64.22.160.180	PTR	mobileiron.citadelgroup.com
64.22.160.180	A	mx-dev.citadelgroup.com
64.22.160.191	A+PTR	name1.citadelgroup.com
64.22.160.191	A	ns1.citadelgroup.info
64.22.160.201	PTR	mail.bridgefield.com
64.22.160.221	PTR	webconf.citadelgroup.com
64.22.160.226	A+PTR	chmivsp01.citadelgroup.com