Before applying for a dot com dot au domain you should be aware of the eligibility rules for these domains that com.au is for commercial purposes.
1. To be eligible for a domain name in com.au , registrants must be:
a) an Australian registered company; or
b) trading under a registered business name in any Australian State or Territory; or
c) an Australian partnership or sole trader;
d) a foreign company licensed to trade in Australia; or
e) an owner of an Australian Registered Trade Mark; or
f) an applicant for an Australian Registered Trade Mark ; or
g) an association incorporated in any Australian State or Territory; or
h) an Australian commercial statutory body.
2. Domain names in com.au must:
a) exactly match, acronym or abbreviation of the registrant’s company or trading name, organization or association name or trademark; or:
b) be otherwise closely and substantially connected to the registrant