The eight-hour lab exam tests your ability to configure actual equipment and troubleshoot the network in a timed test situation. You must make an initial attempt at the CCIE lab exam within 18-months of passing the CCIE written exam. Candidates who do not pass must reattempt the lab exam within 12 months of their last scored attempt in order for their written exam to remain valid. If you do not pass the lab exam within three years of passing the written exam, you must retake the written exam before being allowed to attempt the lab exam again.