Customers took to social media on Thursday afternoon to complain about problems accessing bank services online or through banking applications.
National Australia Bank, along with numerous smaller banks and credit unions, was the only one of the big four banks that was not affected.
Staff at some of the largest banks were unable to access the internet, and the Reserve Bank's website and other services were also unavailable for a length of time.
The Reserve Bank of Australia stated, "We have applied necessary mitigations and the website is now back up and running."
However, according to the ABC, several market operations between the Reserve Bank and commercial banks were canceled today due to technical difficulties experienced by many of the participants.
However, it is understood that the main banks' end-of-day financial settlements were completed as usual.
a tumultuous workplace
Companies used social media to alert their customers to the crisis, even as they struggled to figure out what had gone wrong.
"We're aware that some of you are having trouble accessing our services, and we're looking into it right now," CBA stated on Twitter.
Virgin Australia announced on Twitter that their website and contact center were down due to a system failure.
According to the company, Australia Post was also affected, with an "external outage" disrupting a number of its services.
Services were beginning to be restored by 4 p.m. (AEST), with some bank clients able to log into their apps.
Virgin said it was back up and running just after 5 p.m.
"Virgin Australia is glad to confirm that an IT issue has been addressed, and our website and guest contact centers are back to normal," the airline stated in a statement.
"Flights are generally operating as scheduled, and we apologize for any disruption caused to our guests."
The problem is being blamed on Akamai.
An outage with service provider Akamai was the cause of the incident.
"We were one of many organizations to experience an outage with the Akamai content delivery system today," Virgin Australia stated, "and we are working with them to ensure that required actions are done to avoid these outages from repeating."
Akamai is a content delivery network (CDN), cybersecurity, and cloud service provider based in the United States.
The company bills itself as "the world's largest and most advanced edge platform," to protect platforms and consumers against internet threats while still delivering content rapidly.
Multiple representatives from Akamai have been contacted by the ABC for comment.
The BBC, the Financial Times, and Reddit were among the major worldwide news and media sites that were recently shut down due to an outage at a separate CDN, Fastly.