In prior CCNA exams the "Previous" button was available. Now it is greyed out and they put complex problem at the beginning. Therefore, one cannot get the low hanging fruits first and reserve time to do the complex ones. Also the interactive question in the simulated IOS is too abridged. In the real world you measure many times and cut once with IOS Halp. Please head the above concern. I will write one CCNA on November 6, 2007 and I hope it will be changed. At least activate the "Previous" Button.