Robtex

Up: 68.64.18.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 68.64.19.0/25
Down right: 68.64.19.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
68.64.19.20	PTR	mail1.ord.expertcity.com
68.64.19.195	A+PTR	ns1.citrixonline.biz
68.64.19.195	A+PTR	ns1.expertcity.com
68.64.19.195	PTR	ns2.citrixonline.eu
68.64.19.200	A+PTR	download.citrixonline.com
68.64.19.201	PTR	download.citrixonline.com