The Australian government has ordered an inquiry into a major network failure that hit the country's second-largest telecoms provider, Optus, on Nov 8.

Up to 10 million customers were left without mobile, landline and internet access for more than 12 hours that day, and many utilities and businesses were brought to a standstill.

Industry experts say the catastrophic outage was likely due to a "single point of failure", a lack of backup systems, or both.

Dennis Desmond, a lecturer in cybersecurity, cyber intelligence and cryptography at the School of Science, Technology and Engineering, University of the Sunshine Coast, said it is difficult to say with any degree of certainty what caused the outage, without "knowing the true nature of the outage".

"If we accept Optus' explanation that the outage was a result of a 'technical fault' then we must accept the failure was the result of an internal error, possibly due to a firmware software update, a device replacement or upgrade, or some other human error," he said.

"If it was the result of a firmware of software patch or upgrade, one has to ask whether or not the software was evaluated in a test environment first rather than deploying directly to a live network environment."

Desmond said that if the outage was the result of another kind of human error, Optus needs to be clear about how the error occurred and reassure its customer base that this error will not occur again.

Desmond said that the outage also negatively impacted the other telecoms carriers.

"In this case, the government needs to step in and ensure the carriers work together, have disaster recovery plans, and technologies in place to ensure continued, resilient, and reliable service."

Higher standard

What the government needs to do now is to increase its oversight and hold any organization that is part of the national critical infrastructure to a higher standard of performance, he said.

"The government must ensure that any company that does business in Australia that becomes a part of the critical infrastructure must adhere to very specific requirements that ensures reliability and resilience and a continuity of operations capability," Desmond said.

Konstanty Bialkowski, a senior lecturer at the School of Electrical Engineering and Computer Science at the University of Queensland, said: "I don't believe it is possible to completely make things disaster tolerant."

Australia's communications minister, Michelle Rowland, said on Nov 9 while announcing the inquiry into the Optus outage that the impact of the loss of telecoms connectivity was "concerning".

Apart from the government investigation, Australia's Senate will hold its own inquiry, which will have the power "to compel Optus bosses to appear publicly and provide the answers and the solutions that Australians deserve", inquiry chair Sarah Hanson-Young said.