Vocus response to the enquiry is available from the link below, im not concerned at all, some quotes; (NOTE: the recent dny ddos peaked at over 1Tbps, over 1700x the traffic of the alleged census ddos)
Vocus does not agree that the fourth DDoS attack was the cause of the site becoming unresponsive. The fourth attack comprised of attack traffic which peaked at 563Mbps which is not considered significant in the industry, and lasted 14 minutes. See report from Arbor Networks which indicates that it is materially below the mean attack size (
https://www.arbornetworks.com/images/documents/WISR2016_EN_Web.pdf)."
"The cause of the census website being unreachable was IBM employee’s falsely identifying normal traffic patterns as data exfiltration, and manually turning off their Internet gateway routers"
"Vocus was not, at any time prior to 9 August 2016, invited to participate in any testing of IBM's DDoS mitigation strategy, or given any detail of what testing was undertaken. In fact, Vocus was not informed of IBM’s DDoS mitigation strategy, Island Australia or its specific requirements, until after the fourth attack."
http://www.aph.gov.au/DocumentStore.ashx?id=9f58f27a-9b42-4de1-80f7-60e17edfb153&subId=414847
