The Australian Computer Science Network (ACSnet) was a store-and-forward network used to connect Australia's Universities to each other and to ARPANET. In 1989, with the introduction of AARnet which directly connected Australia's Universities to the Internet, it became obsolete.
It was originally implemented using SUN3 software from Sydney University.
ACSnet connected hosts in Australia resided in a .oz domain, which was moved into the Internet's .au namespace as .oz.au[1].