Robtex

Up: 123.243.12.0/23
Can't show all results, try to descend to a more specific CIDR
Down left: 123.243.13.0/25
Down right: 123.243.13.128/25
(Some of the IP numbers are capped at 3 entries)

IP	Type	Hostname
123.243.13.12	PTR	mail.insightprojects.com.au
123.243.13.14	A+PTR	123-243-13-14.static.tpgi.com.au
123.243.13.15	PTR	mobile.enosys.com.au
123.243.13.26	A+PTR	123-243-13-26.static.tpgi.com.au
123.243.13.33	A+PTR	123-243-13-33.static.tpgi.com.au
123.243.13.84	A	mail.noallco.com.au
123.243.13.100	A	remote.chinatex.com.au
123.243.13.103	A+PTR	123-243-13-103.static.tpgi.com.au
123.243.13.104	A	mail.mediaestablishment.com
123.243.13.110	A+PTR	123-243-13-110.static.tpgi.com.au
123.243.13.123	PTR	123-243-13-123.static.tpgi.com.au
123.243.13.123	A	smtp5.borok.de
123.243.13.123	A	smtp2.irinas-world.de
123.243.13.131	A+PTR	123-243-13-131.static.tpgi.com.au
123.243.13.131	A	lori-cam.com
123.243.13.135	PTR	mail.frenchtravel.com.au
123.243.13.135	A	mail2.frenchtravel.com.au
123.243.13.178	A+PTR	123-243-13-178.static.tpgi.com.au
123.243.13.187	PTR	123-243-13-187.static.tpgi.com.au
123.243.13.196	A	mail.kikkoman.com.au
123.243.13.228	A+PTR	123-243-13-228.static.tpgi.com.au
123.243.13.235	PTR	123-243-13-235.static.tpgi.com.au
123.243.13.235	A	nineworlds.com.au