Robtex

Up: 64.235.136.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 64.235.136.0/23
Down right: 64.235.138.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
64.235.138.3	A+PTR	holua1.sirus.com
64.235.138.4	A+PTR	holua2.sirus.com
64.235.138.9	A+PTR	holua7.sirus.com
64.235.138.10	A+PTR	holua8.sirus.com
64.235.138.15	A+PTR	holua13.sirus.com
64.235.138.19	A+PTR	holua17.sirus.com
64.235.138.21	PTR	holua19.sirus.com
64.235.138.22	A+PTR	holua20.sirus.com
64.235.138.25	A+PTR	holua23.sirus.com
64.235.138.29	A+PTR	holua27.sirus.com
64.235.138.35	A+PTR	holua33.sirus.com
64.235.138.37	A+PTR	holua35.sirus.com
64.235.138.39	A+PTR	holua37.sirus.com
64.235.138.43	A+PTR	holua41.sirus.com
64.235.138.47	A+PTR	holua45.sirus.com
64.235.139.1	PTR	ghlua.sirus.com
64.235.139.19	A+PTR	holub15.sirus.com
64.235.139.21	A+PTR	holub17.sirus.com
64.235.139.34	A+PTR	holub30.sirus.com
64.235.139.36	A+PTR	holub32.sirus.com
64.235.139.46	A+PTR	holub42.sirus.com
64.235.139.52	A+PTR	holub48.sirus.com
64.235.139.71	A+PTR	grlua3.sirus.com
64.235.139.74	A+PTR	grlua6.sirus.com
64.235.139.88	A+PTR	grlua20.sirus.com
64.235.139.95	A+PTR	grlua27.sirus.com
64.235.139.96	A+PTR	grlua28.sirus.com
64.235.139.107	A+PTR	grlua39.sirus.com
64.235.139.139	PTR	miottawa.org
64.235.139.139	A	springlaketwp.org
64.235.139.139	A	co.ottawa.mi.us
64.235.139.141	A+PTR	mail.miottawa.org
64.235.139.143	PTR	mailt.co.ottawa.mi.us
64.235.139.153	PTR	cw-ottawa.miottawa.org
64.235.139.158	PTR	ns.co.ottawa.mi.us
64.235.139.158	A	ns.miottawa.org
64.235.139.194	PTR	mail.oamichigan.com
64.235.139.198	PTR	mail.oamichigan.com
64.235.139.226	PTR	mail.oamichigan.com
64.235.139.226	A	mail.michiganhand.com