Robtex

Up: 124.42.72.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 124.42.76.0/23
Down right: 124.42.78.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
124.42.76.18	PTR	rway.com.cn
124.42.76.18	PTR	vway.com.cn
124.42.76.35	PTR	mail.jjl.cn
124.42.76.35	PTR	mail.jinjilie.com
124.42.76.35	PTR	mail.jjlvisa.com
124.42.76.36	PTR	mail.jjl.cn
124.42.76.36	PTR	mail.jinjilie.com
124.42.76.36	A+PTR	mail.jjlvisa.com
124.42.76.37	PTR	mail.jjl.cn
124.42.76.37	A+PTR	mail.jinjilie.com
124.42.76.37	PTR	mail.jjlvisa.com
124.42.76.59	A	applygmail.com
124.42.76.59	A	studygmail.com
124.42.76.85	A	bobgjs.com
124.42.76.235	PTR	shwf.com.cn
124.42.77.82	A	dairy.cn
124.42.77.189	A	alongit.com.cn
124.42.77.235	A	mgechina.cn
124.42.77.238	A	skilldns.com
124.42.77.250	A	mail.its-cn.cn
124.42.78.30	PTR	sender.csdn.net
124.42.78.41	PTR	mx41.csdn.net
124.42.78.42	PTR	mx42.csdn.net
124.42.78.43	PTR	mx43.csdn.net
124.42.78.44	PTR	mx44.csdn.net
124.42.78.45	PTR	mx45.csdn.net
124.42.78.50	PTR	mail2.csdn.net
124.42.78.51	PTR	mx242.csdn.net
124.42.78.52	PTR	mx243.csdn.net
124.42.78.53	PTR	mx244.csdn.net
124.42.78.54	PTR	mx245.csdn.net
124.42.78.55	PTR	mx252.csdn.net
124.42.78.57	PTR	mx242.csdn.net
124.42.78.58	PTR	mx243.csdn.net
124.42.78.59	PTR	mx244.csdn.net
124.42.78.60	PTR	mx245.csdn.net
124.42.78.61	PTR	mx252.csdn.net
124.42.79.163	A	5dstudy.com
124.42.79.163	A	www.5dstudy.com
124.42.79.163	A	mail.5dstudy.com
124.42.79.197	PTR	crystalcg.com