Robtex

Up: 204.13.0.0/21
Can't show all results, try to descend to a more specific CIDR
Down left: 204.13.4.0/23
Down right: 204.13.6.0/23
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
204.13.4.11	PTR	mail01.digiport.com
204.13.4.11	PTR	mail01.digiport.net
204.13.4.19	PTR	defiant.digiport.com
204.13.4.23	PTR	documents.digiport.com
204.13.4.33	A+PTR	0053-westerndigitek.net.digiport.com
204.13.4.65	A	ptr-mailing.rednodo.com
204.13.4.69	PTR	ptr-server74.rednodo.com
204.13.4.74	A	ptr-server74.rednodo.com
204.13.4.76	PTR	mail76.rednodo.com
204.13.4.76	A	mail.eternallytrendy.com
204.13.4.76	A	mail.compramiami.com
204.13.4.124	PTR	a-124.activefilings.com
204.13.4.124	A	mail.activefilings.com
204.13.4.124	A	ns10.activefilings.com
204.13.4.125	PTR	a-125.activefilings.com
204.13.4.125	A	americanfilings.com
204.13.4.125	A	activefilings.us
204.13.4.161	A+PTR	0079-morrispacific.net.digiport.com
204.13.4.173	A	condoblackbook.net
204.13.4.174	A	condobb.com
204.13.4.174	A	condoblackbook.com
204.13.4.174	A	usefulcrm.net
204.13.4.194	PTR	downtownmiami.com
204.13.4.194	A	playtodaycard.net
204.13.4.194	A	mail.cmgnews.net
204.13.4.195	PTR	buymiami.biz
204.13.4.201	A+PTR	0089-pvg.net.digiport.com
204.13.4.203	A+PTR	mail.pvginsurance.com
204.13.4.203	A	inwoodgroup.com
204.13.4.209	A+PTR	0090-itpceaser.net.digiport.com
204.13.4.210	A	remote.darksidegames.com
204.13.4.217	A+PTR	0091-metropy.net.digiport.com
204.13.4.220	PTR	mail.fembi.com
204.13.4.233	A+PTR	0094-tr8.net.digiport.com
204.13.5.82	A	mail.mediquip-parts.com
204.13.5.85	A+PTR	mail.hosa.com
204.13.5.85	A	mail.miamiobgyns.net
204.13.5.85	A	mx01.hosa.com
204.13.5.86	A	mail.meditechintl.com
204.13.5.185	PTR	mx.lf-mc.com
204.13.5.227	A	brightpc.com
204.13.6.68	A	smtp2.bbsector.net
204.13.6.68	A	mail.mpbox.com
204.13.6.68	A	mpbox.com
204.13.6.90	PTR	colo.wadsworth-law.com
204.13.6.131	A	rscomputers.com
204.13.6.131	A	mail.rscomputers.com
204.13.6.132	PTR	mail.bannersupply.com
204.13.6.132	A	mail.shellow.com
204.13.6.132	A	shellow.com
204.13.6.136	A	thunderboltconverters.com
204.13.6.136	A	thunderboltmufflers.com
204.13.6.136	A	thunderboltexhaust.com
204.13.6.143	A	waterreclamation.com
204.13.6.212	PTR	mx.bestbuddies.com
204.13.6.212	PTR	mx.bestbuddies.org
204.13.7.98	A	mail.taurusmim.com
204.13.7.211	PTR	mail.wdpalaw.com
204.13.7.211	PTR	mail.wdbn.net