"The detail of exactly what happened has not yet been independently reviewed. And as we saw in other stuff-ups, such as Queensland Health, when it was independently reviewed the blame was shared around quite a lot," Mr Noonan said. The attack was either a foreign or locally planned denial of service, or just a "large load" that appeared to be a denial of service but was in fact people trying to fill out the Census, he said. It "beggars belief" IBM's data centre could not handle a denial of service attack, he added."
There's been a bunch of discussion in Australia that there likely had been no "attack" and that it was simply just terrible planning around expected loads the night of the census.