.au is the Internet country code top-level domain (ccTLD) for Australia and it's being administered by .au Domain Administration Ltd (auDA).
It was first created on 5 March 1986. Domain name policy is managed by .au Domain Administration (auDA).
You cannot register a domain name directly under .au. There are more than 10 second-level extensions of .au such as .com.au, .net.au, .id.au, .asn.au, and .org.au. .com.au is the most popular second-level extension of .au.
.au ranks #18 among all domain extensions, and #11 among all country-code extensions (ccTLDs). Currently, there are 2.3M registered .au domain names. auDA is the current registry of .au extension.