Robtex

Up: 216.87.152.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 216.87.152.0/23
Down right: 216.87.154.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
216.87.152.33	PTR	dns2.namecheaphosting.com
216.87.152.33	PTR	dns2.registrar-servers.com
216.87.152.33	PTR	dns4.registrar-servers.com
216.87.153.33	A+PTR	pdns1.registrar-servers.com
216.87.153.33	A+PTR	c22.verisigndns.com
216.87.153.33	A+PTR	c23.verisigndns.com
216.87.154.33	A+PTR	pdns2.registrar-servers.com
216.87.154.33	PTR	c31.verisigndns.com
216.87.154.33	A+PTR	c3.verisigndns.com
216.87.155.33	PTR	dns1.namecheaphosting.com
216.87.155.33	PTR	dns1.registrar-servers.com
216.87.155.33	PTR	dns3.registrar-servers.com