Robtex

Up: 168.0.40.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 168.0.40.0/23
Down right: 168.0.42.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
168.0.40.20	PTR	ns1.portalbits.net.br
168.0.40.21	A+PTR	ns2.portalbits.net.br
168.0.40.42	A+PTR	mail.nortebox.com.br
168.0.40.42	A	mail.portalbits.com.br
168.0.40.42	A	ns1.nortebox.com.br
168.0.40.43	PTR	mail.nortebox.com.br
168.0.40.46	PTR	168-0-40-46.portalbits.net.br
168.0.40.46	A	superbov.com
168.0.40.224	PTR	168.0.40.224.portalbits.net.br