Robtex

Up: 201.139.72.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 201.139.76.0/23
Down right: 201.139.78.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
201.139.76.22	PTR	201.139.76.22.cable.dyn.cableonline.com.mx
201.139.76.102	PTR	201.139.76.102.cable.dyn.cableonline.com.mx
201.139.76.114	PTR	201.139.76.114.cable.dyn.cableonline.com.mx
201.139.76.155	PTR	201.139.76.155.cable.dyn.cableonline.com.mx
201.139.77.37	PTR	201.139.77.37.cable.dyn.cableonline.com.mx
201.139.78.76	PTR	201.139.78.76.cable.dyn.cableonline.com.mx
201.139.78.189	PTR	201.139.78.189.cable.dyn.cableonline.com.mx
201.139.79.10	A+PTR	cmpcablemas.com
201.139.79.10	A	mail.cmpcablemas.com
201.139.79.10	A	root.cmpcablemas.com