Robtex

Up: 72.2.32.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 72.2.36.0/23
Down right: 72.2.38.0/23

IP	Type	Hostname
72.2.36.52	A	cwsexdns.calfrac.com
72.2.36.52	A	dns1.calfrac.com
72.2.36.139	A	restaurantbizmail.com
72.2.36.147	A	fsdmagmail.com
72.2.36.155	A	idaccessmail.com
72.2.36.210	A	selectmailclub.com
72.2.36.251	A	yesmaildeliverability.com
72.2.37.26	PTR	smtp.convenienthomejobcenter.net
72.2.37.37	A	smtp.enews.pdfzone.com
72.2.37.38	PTR	smtp.hustletoprosper.net
72.2.37.38	A	smtp.enews.pdfzone.com
72.2.37.39	PTR	smtp.hustletoprosper.net
72.2.37.39	A	smtp.enews.pdfzone.com
72.2.37.40	PTR	smtp.hustletoprosper.net
72.2.37.40	A	smtp.enews.pdfzone.com
72.2.37.41	A	smtp.enews.pdfzone.com
72.2.37.42	A	smtp.enews.pdfzone.com
72.2.37.43	A	smtp.enews.pdfzone.com
72.2.37.44	PTR	smtp.hustletoprosper.net
72.2.37.44	A	smtp.enews.pdfzone.com
72.2.37.45	PTR	smtp.hustletoprosper.net
72.2.37.45	A	smtp.enews.pdfzone.com
72.2.37.46	PTR	smtp.hustletoprosper.net
72.2.37.46	A	smtp.enews.pdfzone.com
72.2.37.54	PTR	smtp.enews.publish.com
72.2.37.55	PTR	smtp.enews.publish.com
72.2.37.57	PTR	smtp.enews.publish.com
72.2.37.98	A+PTR	ct.enews.tips-it.com
72.2.37.102	PTR	smtp.enews.tips-it.com
72.2.37.104	PTR	smtp.enews.tips-it.com
72.2.37.134	PTR	smtp.enews.cioinsight.com
72.2.37.136	PTR	smtp.enews.cioinsight.com
72.2.37.139	PTR	smtp.enews.cioinsight.com
72.2.37.205	PTR	smtp.eletters.thechannelinsider.com
72.2.38.99	A	information-news.com
72.2.38.115	A	infogroup-news.com
72.2.38.123	A	anegadaoil.com
72.2.38.228	A	surecall4me.com
72.2.38.243	A	directdemo-mail.com
72.2.38.251	A	email.deliverabilitytesting.com
72.2.39.6	A	www.myhelcimstore.com
72.2.39.6	A	www.supplysol.ca
72.2.39.7	A	helcim.com
72.2.39.13	PTR	smtp.roaringhomejob.com
72.2.39.18	A	anchortech.ca
72.2.39.46	PTR	smtp.cash-in-1-hour-offer.com
72.2.39.203	A	staging10.yesmailexpress.com
72.2.39.219	A	magellan-yme.com
72.2.39.221	A	smtp.magellan-yme.com
72.2.39.222	A	smtp.magellan-yme.com
72.2.39.227	A	magellan2-yme.com
72.2.39.229	A	smtp.magellan2-yme.com
72.2.39.230	A	smtp.magellan2-yme.com
72.2.39.237	A	smtp.hkdev1.yesmail-root.com
72.2.39.238	A+PTR	smtp.hkdev1.yesmail-root.com