Robtex

Up: 168.121.0.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 168.121.4.0/23
Down right: 168.121.6.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
168.121.4.5	PTR	168-121-4-5.granditelecom.com.br
168.121.4.5	A	as1.granditelecom.com.br
168.121.4.6	A	as2.granditelecom.com.br
168.121.4.248	PTR	168-121-4-248.granditelecom.com.br
168.121.4.248	A	ideiaembalagens.com
168.121.5.3	PTR	168-121-5-3.granditelecom.com.br
168.121.6.4	PTR	168-121-6-4.granditelecom.com.br
168.121.6.4	A	caiadopn.com
168.121.6.4	A	mail.caiadopn.com
168.121.6.14	PTR	168-121-6-14.granditelecom.com.br
168.121.6.131	A+PTR	deb9-brdsoft.brdsoft.com.br
168.121.6.131	A	brdsoft.com.br
168.121.6.131	A	meuprinting.com
168.121.6.134	A+PTR	zimbra.pastoredson.com.br
168.121.6.134	A	zimbra.brdsoft.com.br
168.121.6.134	A	zimbra.granditelecom.com.br
168.121.6.135	PTR	168-121-6-135.granditelecom.com.br
168.121.6.135	A	ns1.pastoredson.com.br
168.121.6.136	A	ns2.pastoredson.com.br
168.121.6.136	A	ns2.praczyk.com.br
168.121.6.136	A	ns2.brdsoft.com.br
168.121.6.137	PTR	168-121-6-137.granditelecom.com.br
168.121.6.137	A	orandopeloparana.com.br
168.121.6.138	PTR	168-121-6-138.granditelecom.com.br