.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 domain extension ranks #19 among all domain extensions, and #12 among all country-code extensions (ccTLDs). Currently, there are 2.4 Million registered .au domain names. .au Domain Administration (auDA) is the registry of .au extension.
The most popular .au domain name is google.com.au. Its worldwide rank is 364.