The website Domainer claims the domain was meant to be used for running the .au domain registry, so that auDA would not need an outside agency to carry out this function.
A communique from the auDA board after a special general meeting in August 2017 says: "A Board resolution to change auDA’s brand to auHQ will be put to members for their input."
An auDA spokesperson said the domain was registered in 2017 for "a proposed brand initiative which has been discontinued". The initiative was not specified.
The auDA spokesperson said: "In addition to the domain name, auDA also registered the business name and the corresponding trademarks.
"The name never had any association, relevance or connection whatsoever to the .au domain registry. The domain name expired and was placed on the 'drop list' as per normal practice."
The spokesperson added: "Names acquired from the drop list are subject to the same eligibility requirements as other .au domain names. It is up to registrants to ensure they meet those eligibility requirements and the circumstance is no different for the new registrant of auhq.com.au."