Dubai labor law / work ban?

my bro was terminated from his job last november. he was told that he wont be able to apply for a new job bec of the 6mon ban. when does the ban takes effect - upon work termination or after his visa expires? Can he still get the NOC from his previous company even after 2months has ped since he was terminated? Is the ban applicable to all who did not finish their contract - either terminated or resigned?