The testing interface itself will not lock you out if you go over your 24 hour allotted time. However, during grading I will roll back your answers to those submitted within the 24 hour period. (Note: the exam system keeps track of all answers you submit and the time at which you submit them, not just when you click the final "Submit" button for the entire test, but each time you answer a question and then move on to another question. Therefore I can see not only your final answers, but all earlier versions of those answers as well.)
If technical difficulties arise that make it impossible for you to complete the exam within the allotted time, you should go ahead and complete it as quickly as possible, then send e-mail to zeil@cs.odu.edu detailing the nature of the problem, and I will take that under advisement in deciding whether to accept you late answers. To take the final exam, click here.