The NZ stock exchange is having issues with DOS attacks .

An 'expert' interviewed on the radio made the claim that this DOS attack could have been easily negated , and he seemed to imply the NZX's IT didnt know what they were doing.

Just wondering,
is that 'expert' opinion just BS , Its hard to imagine that NZX dont have competent IT .
Is that just theory vs real life ?
Does claimed 'DOS protection" in hardware firewalls actually work against determined prolonged attacks , from botnets ?

Would a competent hacker attacking NZX not get around any measures put in to mitigate DOS attacks .