Robtex

Up: 123.0.224.0/19
Can't show all results, try to descend to a more specific CIDR
Down left: 123.0.240.0/21
Down right: 123.0.248.0/21
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
123.0.240.240	PTR	123-0-240-240.nty.dy.tbcnet.net.tw
123.0.241.195	PTR	123-0-241-195.nty.dy.tbcnet.net.tw
123.0.242.82	PTR	123-0-242-82.nty.dy.tbcnet.net.tw
123.0.243.65	PTR	123-0-243-65.nty.dy.tbcnet.net.tw
123.0.243.225	PTR	123-0-243-225.nty.dy.tbcnet.net.tw
123.0.244.112	PTR	123-0-244-112.nty.dy.tbcnet.net.tw
123.0.244.170	A	x37tw.com
123.0.244.170	A	ns1.x37tw.com
123.0.244.170	A	ns2.x37tw.com
123.0.244.244	A	oemone.com.tw
123.0.244.244	A	mail.oemone.com.tw
123.0.245.177	PTR	123-0-245-177.nty.dy.tbcnet.net.tw
123.0.249.78	A	5187i.com
123.0.249.80	PTR	123-0-249-80.nty.dy.tbcnet.net.tw
123.0.249.162	PTR	123-0-249-162.nty.dy.tbcnet.net.tw
123.0.249.243	PTR	123-0-249-243.nty.dy.tbcnet.net.tw
123.0.250.195	PTR	123-0-250-195.nty.dy.tbcnet.net.tw
123.0.250.247	A	ns.agi.idv.tw
123.0.250.247	A	tw.autoglassweb.net
123.0.250.247	A	smtp.agi.idv.tw
123.0.251.17	PTR	123-0-251-17.nty.dy.tbcnet.net.tw
123.0.252.97	PTR	123-0-252-97.nty.dy.tbcnet.net.tw
123.0.252.179	PTR	123-0-252-179.nty.dy.tbcnet.net.tw
123.0.253.16	PTR	123-0-253-16.nty.dy.tbcnet.net.tw
123.0.253.51	PTR	123-0-253-51.nty.dy.tbcnet.net.tw
123.0.253.114	PTR	123-0-253-114.nty.dy.tbcnet.net.tw
123.0.253.130	PTR	123-0-253-130.nty.dy.tbcnet.net.tw
123.0.253.178	PTR	123-0-253-178.nty.dy.tbcnet.net.tw
123.0.254.83	PTR	123-0-254-83.nty.dy.tbcnet.net.tw
123.0.254.145	PTR	123-0-254-145.nty.dy.tbcnet.net.tw