Robtex

Up: 138.121.48.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 138.121.52.0/23
Down right: 138.121.54.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
138.121.52.0	PTR	138-121-52-0.signetx.com.br
138.121.52.4	PTR	ns1.signetx.com.br
138.121.52.4	A	ns2.signetx.com.br
138.121.52.4	A	speedtest.signetcaratinga.com.br
138.121.52.8	PTR	138-121-52-8.signetx.com.br
138.121.52.26	PTR	138-121-52-26.signetx.com.br
138.121.52.26	A	dpcpolibras.ddns.net
138.121.52.28	PTR	138-121-52-28.signetx.com.br
138.121.52.28	A	ns1.doctumtv.com.br
138.121.52.30	PTR	alpha1.dpcnet.com.br
138.121.52.30	A	dpclogistica.com.br
138.121.52.30	A	aeroportodecaratinga.com.br
138.121.52.70	PTR	138-121-52-70.signetx.com.br
138.121.52.70	A	7052121138.signet.com.br
138.121.52.74	A+PTR	138-121-52-74.signetx.com.br
138.121.52.86	PTR	138-121-52-86.signetx.com.br
138.121.52.86	A	8652121138.signet.com.br
138.121.52.87	PTR	138-121-52-87.signetx.com.br
138.121.52.87	A	8752121138.signet.com.br
138.121.52.98	PTR	138-121-52-98.signetx.com.br
138.121.52.98	A	9852121138.signet.com.br
138.121.52.126	PTR	138-121-52-126.signetx.com.br
138.121.52.126	A	12652121138.signet.com.br
138.121.52.190	A+PTR	19052121138.signet.com.br
138.121.52.215	A+PTR	21552121138.signet.com.br
138.121.52.218	PTR	138-121-52-218.signetx.com.br
138.121.52.218	A	21852121138.signet.com.br
138.121.52.226	PTR	138-121-52-226.signetx.com.br
138.121.52.226	A	22652121138.signet.com.br
138.121.52.229	PTR	138-121-52-229.signetx.com.br
138.121.52.229	A	22952121138.signet.com.br
138.121.52.255	PTR	138-121-52-255.signetx.com.br
138.121.53.0	PTR	138-121-53-0.signetx.com.br
138.121.53.124	PTR	stable124.dpcnet.com.br
138.121.53.194	A+PTR	19453121138.signet.com.br
138.121.53.197	A+PTR	19753121138.signet.com.br
138.121.53.250	A+PTR	25053121138.signet.com.br
138.121.54.0	PTR	054121138.signet.com.br
138.121.54.10	A+PTR	1054121138.signet.com.br
138.121.54.15	A+PTR	1554121138.signet.com.br
138.121.54.38	A+PTR	3854121138.signet.com.br
138.121.54.101	A+PTR	10154121138.signet.com.br
138.121.54.218	A+PTR	21854121138.signet.com.br
138.121.54.224	A+PTR	22454121138.signet.com.br
138.121.54.230	A+PTR	23054121138.signet.com.br
138.121.55.9	A+PTR	955121138.signet.com.br
138.121.55.11	A+PTR	1155121138.signet.com.br
138.121.55.15	A+PTR	1555121138.signet.com.br
138.121.55.24	A+PTR	2455121138.signet.com.br
138.121.55.53	A+PTR	5355121138.signet.com.br
138.121.55.218	A+PTR	21855121138.signet.com.br
138.121.55.241	A+PTR	24155121138.signet.com.br
138.121.55.247	PTR	24755121138.signet.com.br
138.121.55.247	A	ns2.signet.com.br
138.121.55.247	A	ns2.dpclog.com.br
138.121.55.251	PTR	25155121138.signet.com.br
138.121.55.252	PTR	25255121138.signet.com.br
138.121.55.252	A	ns1.signet.com.br
138.121.55.252	A	ns1.dpclog.com.br
138.121.55.253	A+PTR	25355121138.signet.com.br
138.121.55.255	PTR	25555121138.signet.com.br