Robtex

Up: 123.51.16.0/20
Can't show all results, try to descend to a more specific CIDR
Down left: 123.51.16.0/22
Down right: 123.51.20.0/22

IP	Type	Hostname
123.51.16.186	PTR	123-51-16-186.static.dsl.net.au
123.51.20.56	PTR	123-51-20-56.static.dsl.net.au
123.51.21.123	PTR	123-51-21-123.static.dsl.net.au
123.51.22.3	PTR	123-51-22-3.static.dsl.net.au
123.51.22.12	A	maclagan.com.au
123.51.22.118	A	mail.wum.com.au
123.51.22.146	PTR	123-51-22-146.static.dsl.net.au
123.51.22.146	A	corp.annett.com.au
123.51.22.147	A	mail.annett.com.au
123.51.23.3	PTR	123-51-23-3.static.dsl.net.au
123.51.23.3	A	mail.shw.com.au
123.51.23.4	PTR	123-51-23-4.static.dsl.net.au
123.51.23.4	A	mail.alpharehab.com.au
123.51.23.30	A	mail.hunterpumps.com
123.51.23.153	PTR	123-51-23-153.static.dsl.net.au