Robtex

Up: 163.53.22.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 163.53.23.0/25
Down right: 163.53.23.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
163.53.23.14	A	smtp.breakfastpoint.com
163.53.23.14	A	mail.breakfastpoint.com
163.53.23.14	A	mail.rosecorp.net.au
163.53.23.19	A+PTR	rww.karras.com.au
163.53.23.22	A+PTR	mail.megasealed.com.au
163.53.23.22	A	smtp.megasealed.com.au
163.53.23.31	A	mail.pivotal.com.au
163.53.23.33	A	owa.cantoo.org.au
163.53.23.34	PTR	exchange.321.com.au
163.53.23.34	A	mail.axiomcc.com.au
163.53.23.34	A	mail.cityorchids.com
163.53.23.36	A+PTR	spam.321.com.au
163.53.23.36	A	mail.funenterprises.com.au
163.53.23.36	A	mail.australismusic.com.au
163.53.23.37	A+PTR	ns1.321.com.au
163.53.23.37	A	mx1.321.com.au
163.53.23.38	A	leaderhvac.com.au
163.53.23.38	A	curecards.org.au
163.53.23.38	A	nuvision.com.au
163.53.23.40	A	pop.321.com.au
163.53.23.41	A	www.workingtech.com
163.53.23.42	A	mail.workingtech.com
163.53.23.44	A	321.com.au
163.53.23.44	A	www.321.com.au
163.53.23.45	A	firstpath.com.au
163.53.23.65	A	bealepianos.com.au
163.53.23.65	A	www.ashtonmusic.com
163.53.23.65	A	www.stagesystems.com.au
163.53.23.90	A+PTR	filter.321.com.au
163.53.23.93	A	mail.unrefugees.org.au