Robtex

Up: 64.22.160.0/19
Can't show all results, try to descend to a more specific CIDR
Down left: 64.22.160.0/21
Down right: 64.22.168.0/21
(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
64.22.160.16	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	citadelgroup.co.uk
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
64.22.161.1	A+PTR	cit2.citadelgroup.com
64.22.161.12	A	mx3.rmvcommunications.com
64.22.161.13	A+PTR	mx3.citadelgroup.com
64.22.161.13	A	mx3.citidelgroup.com
64.22.161.32	A	sys2.citadelgroup.com
64.22.161.45	A+PTR	dns4.citadelgroup.com
64.22.161.45	A	metalogicsoftware.com
64.22.161.45	A	www.metalogic.com
64.22.161.50	A	ns6.citadelgroup.info
64.22.161.50	A	ns6.citadelgroup.com
64.22.161.50	A	ns2.griffincares.net
64.22.161.144	A+PTR	mti2.citadelgroup.com
64.22.161.145	A	mto2.citadelgroup.com
64.22.161.191	PTR	name1.citadelgroup.com
64.22.161.191	A	name2.citadelgroup.com
64.22.161.191	A	ns2.citadelgroup.info
64.22.163.32	PTR	access.citadelsecurities.com
64.22.164.12	PTR	mobile.citadelgroup.com
64.22.164.16	A	crm.citadelgroup.com
64.22.164.24	A	ctecsw.com
64.22.164.29	A	cesaccess.citadelsecurities.com
64.22.164.32	PTR	citsec.citadelsecurities.com
64.22.164.32	A	access.citadelsecurities.com
64.22.164.35	A	www.citadelgroup.com
64.22.164.35	A	www.citinv.com
64.22.164.36	A	ns1.citadelgroup.com
64.22.164.49	A	viewpoint.citadelgroup.com
64.22.164.53	PTR	www.citadel.com
64.22.164.53	A	mail.datastandardsworkinggroup.org
64.22.164.53	A	citadelgroup.co.uk