Robtex

Up: 138.0.72.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 138.0.72.0/23
Down right: 138.0.74.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
138.0.72.10	PTR	ns1.ultrafilbra.net.br
138.0.72.10	A	speedtest3.ultranetce.com.br
138.0.72.10	A	ns1.ultranetce.com.br
138.0.72.11	PTR	speedtest2.ultrafibra.net.br
138.0.72.11	PTR	speedtest.ultrafibra.net.br
138.0.72.11	A+PTR	ns2.ultrafibra.net.br
138.0.72.18	A	ultralinkce.com.br
138.0.72.156	PTR	138-0-72-156.ultrafibra.net.br
138.0.73.2	PTR	tsunaminet.ultrafibra.net.br
138.0.73.2	A	tsunaminetce.com.br
138.0.73.22	A	ns2.ultranetce.com.br
138.0.73.34	PTR	c001.for001.ultranetce.isp.nflxvideo.net
138.0.73.45	PTR	138-0-73-45.ultrafibra.net.br
138.0.73.45	A	provedorflashnet.com.br
138.0.73.76	PTR	cache.google.com
138.0.73.76	A	r1---sn-0aug5oxujx-4vge.googlevideo.com
138.0.73.77	PTR	cache.google.com
138.0.73.78	PTR	cache.google.com
138.0.73.78	A	r3.sn-0aug5oxujx-4vge.googlevideo.com
138.0.73.159	PTR	138-0-73-159.teclon.com.br
138.0.73.159	A	www.teclon.com.br
138.0.73.250	PTR	138-0-73-250.ultranetce.com.br
138.0.73.250	A	ultranetce.com.br
138.0.73.250	A	speedtest.ultrafibra.net.br
138.0.74.6	PTR	138-0-74-6.conectmais.com.br
138.0.74.6	A	conectmais.com.br
138.0.74.6	A	www.conectmais.com.br
138.0.74.81	PTR	138-0-74-81.ultranetce.com.br
138.0.74.81	A	scontent.fqbx2-1.fna.fbcdn.net
138.0.74.97	PTR	138-0-74-97.ultranetce.com.br
138.0.74.97	A	instagram.fqbx2-1.fna.fbcdn.net
138.0.74.188	PTR	138-0-74-188.ultrafibra.net.br
138.0.74.188	A	ultlink.com.br
138.0.74.198	PTR	138-0-74-198.ultrafibra.net.br
138.0.74.198	A	lisieux.com.br
138.0.75.6	A	zonnetprovedor.net.br