Robtex

Up: 69.56.16.0/20
Can't show all results, try to descend to a more specific CIDR
Down left: 69.56.16.0/22
Down right: 69.56.20.0/22
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
69.56.16.2	A	mta.skylist.com
69.56.18.25	A+PTR	mail1.email.carnegiecomm.com
69.56.18.26	A	mail2.email.carnegiecomm.com
69.56.18.27	PTR	mail3.members.alloyeducation.com
69.56.18.27	A	mail3.email.carnegiecomm.com
69.56.18.28	A	mail4.email.carnegiecomm.com
69.56.18.32	A	members.alloystudentoffers.com
69.56.18.33	A	mail1.members.alloystudentoffers.com
69.56.18.34	A	mail2.members.alloystudentoffers.com
69.56.18.35	A	mail3.members.alloystudentoffers.com
69.56.18.40	A+PTR	click1.members.privatecolleges.com
69.56.18.40	A	webmail.members.privatecolleges.com
69.56.18.40	A	mail.members.privatecolleges.com
69.56.18.48	PTR	click1.members.collegexpress.com
69.56.18.48	A	members.collegexpress.com
69.56.18.49	PTR	mail1.members.collegexpress.com
69.56.18.50	PTR	mail2.members.collegexpress.com
69.56.18.51	PTR	mail3.members.collegexpress.com
69.56.18.52	A	mail4.members.collegexpress.com
69.56.18.55	A	mail7.members.collegexpress.com
69.56.19.16	A	webmail.members.vault.com
69.56.19.16	A	click1.members.vault.com
69.56.19.16	A	members.vault.com
69.56.19.24	PTR	click1.info.vault.com
69.56.19.24	A	info.vault.com
69.56.19.25	A	mail1.info.vault.com
69.56.19.26	A	mail2.info.vault.com
69.56.19.27	PTR	mail3.info.vault.com
69.56.19.31	A	mail7.info.vault.com
69.56.19.32	A	careerinsider-news.vault.com
69.56.19.34	A	mail2.careerinsider-news.vault.com
69.56.19.40	PTR	click1.email.infobaselearning.com
69.56.19.40	A	email.infobaselearning.com
69.56.19.43	A	mail3.email.infobaselearning.com
69.56.20.8	A+PTR	mail1.newsletters.wnd.com
69.56.20.9	A+PTR	mail2.newsletters.wnd.com
69.56.20.10	A+PTR	mail3.newsletters.wnd.com
69.56.20.11	A+PTR	mail4.newsletters.wnd.com
69.56.20.176	A	gclexpertsnews.com
69.56.20.177	A+PTR	mail1.gclexpertsnews.com
69.56.20.178	A	mail2.gclexpertsnews.com
69.56.20.179	A+PTR	mail3.gclexpertsnews.com
69.56.20.184	A	etype-mail.com
69.56.20.185	A	mail1.etype-mail.com
69.56.20.186	A	mail2.etype-mail.com
69.56.20.187	A	mail3.etype-mail.com
69.56.20.192	PTR	click1.usafismembersclub.com
69.56.20.192	A	hostmaster.usafismembersclub.com
69.56.20.192	A	*.usafismembersclub.com
69.56.20.193	PTR	mail1.usafismembersclub.com
69.56.20.194	PTR	mail2.usafismembersclub.com
69.56.20.195	PTR	mail3.usafismembersclub.com
69.56.20.229	A	mail1.iwon-updates.com
69.56.20.242	A	mail6.excite-updates.com
69.56.20.243	A	mail7.excite-updates.com
69.56.21.25	A+PTR	mail1.progcorp.com
69.56.21.26	A+PTR	mail2.progcorp.com
69.56.21.27	PTR	mail3.progcorp.com
69.56.21.28	PTR	click1.skillful-executive.com
69.56.21.28	PTR	click1.pbpexecreports.com
69.56.21.28	PTR	click1.safetynews-alert.com
69.56.21.32	A+PTR	mail2.itmanager-daily.com
69.56.21.33	A+PTR	mail1.customerexperience-insight.com
69.56.21.34	A+PTR	mail2.customerexperience-insight.com
69.56.21.35	A+PTR	mail1.cfo-dailynews.com
69.56.21.40	A+PTR	mail2.healthcarebusiness-tech.com
69.56.21.51	A+PTR	mail1.pbpexecreports.com
69.56.21.52	A+PTR	mail2.pbpexecreports.com
69.56.21.53	A	mail1.higheredhero.com
69.56.21.54	A	mail2.higheredhero.com
69.56.21.64	A	click1.executiveonlinecontent.com
69.56.21.65	A	mail1.executiveonlinecontent.com
69.56.21.66	A	mail2.executiveonlinecontent.com
69.56.21.71	A+PTR	mail3.advanceyourcareers.com
69.56.21.72	A+PTR	mail1.pbpexecutivereports.net
69.56.21.73	A+PTR	mail2.pbpexecutivereports.net
69.56.21.74	PTR	mail1.pbp-reports.net
69.56.21.75	A+PTR	mail2.pbp-reports.net
69.56.21.77	A	mail2.pbp-execreports.net
69.56.21.80	A+PTR	mail1.mylaborlawalerts.com
69.56.21.81	A+PTR	mail2.mylaborlawalerts.com