auDA stands for .au Domain Administration Limited.
It is the .au domain registry and a not-for-profit organisation that runs all second and third-level .au domains (.au, .com.au, .net.au, .org.au, .id.au and so on).
They work with a range of stakeholders including industry, government, law enforcement and the Australian and international community to develop and administer the rules for domains in the .au namespace.