Robtex

Up: 208.247.0.0/20
Can't show all results, try to descend to a more specific CIDR
Down left: 208.247.0.0/22
Down right: 208.247.4.0/22

IP	Type	Hostname
208.247.0.1	PTR	firewall.alerts.com
208.247.0.8	PTR	dyn8.alertmewhen.com
208.247.0.11	PTR	dyn11.alertmewhen.com
208.247.1.233	PTR	208-247-1-233.ded.btitelecom.net
208.247.1.250	PTR	208-247-1-250.ded.btitelecom.net
208.247.2.34	PTR	208-247-2-34.ded.btitelecom.net
208.247.2.128	PTR	208-247-2-128.ded.btitelecom.net
208.247.2.185	PTR	208-247-2-185.ded.btitelecom.net
208.247.3.98	PTR	nrt.com
208.247.3.194	PTR	dailyval.com
208.247.4.254	PTR	mail.leonardusa.com
208.247.5.2	PTR	dyn2.micromedium.com