The .com.au Domain
.COM.AU is the country-specific top-level domain for commercial organisations in the Commonwealth of Australia, which is largely referred to as Australia. Although the largest city is the metropolis Sydney, the capital of Australia is Canberra. As one of the wealthiest countries in the world, Australia has significant resources and a modern service economy that makes the Australian dollar such a strong currency.
With your .com.au domain, you instantly show that you have a long-term interest in your business relationships in Australia and at the same time benefit from a strong, search engine relevant top level domain.