.com.au is used by commercial entities such as companies with an Australian Company Number and businesses registered with State governments.
.net.au is recommended for organizations and companies that are using the Internet as an integral part of their operations.
.id.au is reserved for the people of Australia to create their own online identity.
.asn.au is for incorporated associations, trade unions, political parties, sporting and special interest clubs, and partnerships between disparate organisations.
.org.au is for verifiable non-profit and charitable organisations.