Robtex

Up: 191.6.56.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 191.6.56.0/25
Down right: 191.6.56.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
191.6.56.60	PTR	ns3.entornet.com.br
191.6.56.106	A+PTR	ns1.entornet.com.br
191.6.56.106	A	ispadmin.entornet.com.br
191.6.56.106	A	luiz.entornet.com.br
191.6.56.107	A+PTR	ns2.entornet.com.br
191.6.56.108	A+PTR	ns.entornet.com.br