Robtex

Up: 123.51.128.0/20
Can't show all results, try to descend to a more specific CIDR
Down left: 123.51.128.0/22
Down right: 123.51.132.0/22
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
123.51.128.0	PTR	123.51.128.0.ll.static.sparqnet.net
123.51.128.2	PTR	123.51.128.2.ll.static.sparqnet.net
123.51.128.9	PTR	123.51.128.9.ll.static.sparqnet.net
123.51.128.10	PTR	123.51.128.10.ll.static.sparqnet.net
123.51.128.11	PTR	123.51.128.11.ll.static.sparqnet.net
123.51.128.17	PTR	123.51.128.17.ll.static.sparqnet.net
123.51.128.18	PTR	123.51.128.18.ll.static.sparqnet.net
123.51.128.49	PTR	123.51.128.49.ll.static.sparqnet.net
123.51.128.56	PTR	123.51.128.56.ll.static.sparqnet.net
123.51.128.64	PTR	123.51.128.64.ll.static.sparqnet.net
123.51.128.75	PTR	123.51.128.75.ll.static.sparqnet.net
123.51.128.80	PTR	123.51.128.80.ll.static.sparqnet.net
123.51.128.82	PTR	123.51.128.82.ll.static.sparqnet.net
123.51.128.89	PTR	123.51.128.89.ll.static.sparqnet.net
123.51.128.90	PTR	123.51.128.90.ll.static.sparqnet.net
123.51.128.91	PTR	123.51.128.91.ll.static.sparqnet.net
123.51.128.96	PTR	123.51.128.96.ll.static.sparqnet.net
123.51.128.98	PTR	123.51.128.98.ll.static.sparqnet.net
123.51.128.105	PTR	123.51.128.105.ll.static.sparqnet.net
123.51.128.112	PTR	123.51.128.112.ll.static.sparqnet.net
123.51.128.114	PTR	123.51.128.114.ll.static.sparqnet.net
123.51.128.115	PTR	123.51.128.115.ll.static.sparqnet.net
123.51.128.120	PTR	123.51.128.120.ll.static.sparqnet.net
123.51.128.122	PTR	123.51.128.122.ll.static.sparqnet.net
123.51.128.137	PTR	123.51.128.137.ll.static.sparqnet.net
123.51.128.145	PTR	123.51.128.145.ll.static.sparqnet.net
123.51.128.147	PTR	123.51.128.147.ll.static.sparqnet.net
123.51.128.168	PTR	123.51.128.168.ll.static.sparqnet.net
123.51.128.171	PTR	123.51.128.171.ll.static.sparqnet.net
123.51.128.194	PTR	123.51.128.194.ll.static.sparqnet.net
123.51.128.200	A	samoa-quaff.com
123.51.128.200	A	mail.samoa-quaff.com
123.51.128.202	PTR	123.51.128.202.ll.static.sparqnet.net
123.51.128.217	PTR	123.51.128.217.ll.static.sparqnet.net
123.51.128.233	PTR	123.51.128.233.ll.static.sparqnet.net
123.51.128.234	PTR	123.51.128.234.ll.static.sparqnet.net
123.51.128.240	PTR	123.51.128.240.ll.static.sparqnet.net
123.51.128.248	PTR	123.51.128.248.ll.static.sparqnet.net
123.51.132.120	A	web1.ivan.com.tw
123.51.132.120	A	ivandns.ivan.com.tw
123.51.132.121	A	ivanweb.ivan.com.tw
123.51.132.152	A	folks.com.tw
123.51.132.175	A	ms1.recovery.org.tw
123.51.133.5	A	www.jjn.com.tw
123.51.133.5	A	dns.jjn.com.tw
123.51.133.5	A	ns.jjn.com.tw
123.51.133.20	A	eip.jtv.com.tw
123.51.133.43	A	mg2.tna.com.tw
123.51.133.140	A	www.6th.com.tw
123.51.133.140	A	mail.jyico.com.tw
123.51.133.140	A	www.2888.com.tw
123.51.133.166	A+PTR	spam1.taichia.com.cn
123.51.133.166	A+PTR	spam1.yangshen-ch.com.cn
123.51.133.166	A+PTR	spam1.grandmax.com.tw