Robtex

Up: 72.133.0.0/18
Can't show all results, try to descend to a more specific CIDR
Down left: 72.133.0.0/20
Down right: 72.133.16.0/20

IP	Type	Hostname
72.133.2.131	PTR	mta-72-133-2-131.kc.rr.com
72.133.3.2	PTR	mta-72-133-3-2.kc.rr.com
72.133.3.193	PTR	mta-72-133-3-193.kc.rr.com
72.133.3.225	PTR	mta-72-133-3-225.kc.rr.com
72.133.4.163	PTR	mta-72-133-4-163.kc.rr.com
72.133.6.2	PTR	mta-72-133-6-2.kc.rr.com
72.133.8.2	PTR	mta-72-133-8-2.kc.rr.com
72.133.9.65	PTR	mta-72-133-9-65.kc.rr.com
72.133.9.192	PTR	mta-72-133-9-192.kc.rr.com
72.133.13.2	PTR	mta-72-133-13-2.kc.rr.com
72.133.16.2	PTR	mta-72-133-16-2.kc.rr.com
72.133.16.130	PTR	mta-72-133-16-130.kc.rr.com
72.133.24.0	PTR	mta-72-133-24-0.kc.rr.com
72.133.27.1	PTR	mta-72-133-27-1.kc.rr.com
72.133.27.2	PTR	mta-72-133-27-2.kc.rr.com
72.133.27.128	PTR	mta-72-133-27-128.kc.rr.com
72.133.27.160	PTR	mta-72-133-27-160.kc.rr.com
72.133.30.2	PTR	mta-72-133-30-2.kc.rr.com