Robtex

Up: 123.51.128.0/18
Can't show all results, try to descend to a more specific CIDR
Down left: 123.51.128.0/20
Down right: 123.51.144.0/20
(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
123.51.128.64	PTR	123.51.128.64.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
123.51.128.194	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
123.51.132.120	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
123.51.133.43	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
123.51.136.17	A	mail.millenniumtaichung.com
123.51.136.20	A	spam.millenniumtaichung.com
123.51.136.49	A	www.tahchung.com.tw
123.51.136.74	A	tipsreal.com
123.51.136.79	A	twtimes.tw
123.51.136.82	A	fengsui.com.tw
123.51.136.82	A	www.fengsui.com.tw
123.51.144.43	A	www.ccp.com.tw
123.51.144.43	A	www.ccpgp.com
123.51.145.26	A	www.wpgdadatong.com
123.51.145.27	A	www.wpgdadawant.com
123.51.145.44	A	tvt.com.tw
123.51.145.44	A	ftv.com.tw
123.51.145.75	A+PTR	mailsrv.repon.com.tw
123.51.145.75	A	tpe200wan1.nanjuen.com.tw
123.51.148.20	A	www.ipost.com.tw
123.51.152.19	A	mdm.asus.com
123.51.152.38	A	medflybiopharm.com
123.51.152.161	A	dq2spftp.sysnet.net.tw
123.51.155.9	A+PTR	appbackend.dreammall.com.tw