On Server Room entrance. They know how much security is important in server environment so they decided to put this code-lock in the door.
What do you think about that ? :) Of course it's a rhetoric question ! It's very easy to guess the 4 digit unlock pin. Moreover you might think that the # is used as "Enter Key" and that there are not one digit passwords, like for example 8888 or 9999 because both buttons are spoiled. So, you need 16 - 2 = 14 attempts in order to guess the right pin, that means in average it takes only 7 attempts to guess the correct sequence and enter into server room ! Cool, isn't it ?
