Gardaí are investigating a number of alleged cyber attacks on the website of the Central Applications Office (CAO) earlier this week.
The denial-of-service attacks restricted access to the website on Monday for thousands of Leaving Cert students checking the first round of third level course offers.
It was also forced to shut down its website on Wednesday after another attack resulted in new passwords being issued to 22,000 users.
Operations manager Joseph O’Grady said the attacks had been reported to the gardaí and that the body had supplied logs of website traffic to aid the investigation.
Mr O’Grady said fake IP addresses were usually used by the perpetrators of such attacks and that they were very difficult to trace.
He told RTÉ Radio that he did not know why somebody would target the website at its busiest time and that both internal and external staff would be manning the site next Thursday to ensure there were no problems when second round offers were issued.
A Garda spokesman confirmed an investigation into the incident had begun.
The majority of visitors to the site were met by a message that the site was undergoing maintenance, and they were unable to accept their course offers.
A denial-of-service attack is a type of cyber crime which often occurs when criminals or hackers create a network of computers using software downloaded by their unsuspecting owners.
The computers are then directed to send multiple page requests to a specific web address, overwhelming it with traffic and preventing it from responding to legitimate users.
The motives behind cyber attacks are often financial, and online bookmakers are known to have been blackmailed ahead of major sporting events.
