The best thing to do would be to close out the window and pick up your work whenever you have a chance to do so. This may not be the answer you are looking for and I don't have one of the HOLs in front of me but it will pretty much do the same thing as clicking an [exit] button. As far as stopping the "timer", there is no way to stop the HOL timer. You can extend the time limit twice but that's about it. The HOLs are setup with a maximum time limit on purpose. Because they are free to the public, resources come at a premium. Because of the cost of resources that are being lent to the public, they have to limit people squatting on resources...so to speak. Your best bet is to allocate a windows from 1-3.5 hours at a maximum to perform the whole lab. If you cannot finish in time or get interrupted, then just restart the lab. I had to restart the lab 3-5 times but each time, the preliminary setup steps go quicker and are expected. Then just pick up where you left off and try to finish the lab in as few as possible iterations. Unless you're lightning fast at reading and understanding a new topic (which defies purpose of going through HOLs...since you're there to learn something new), it's pretty much expected you have to re-enroll in some of the labs..especially the NSX ones. Before I implemented NSX from ground up, I reregistered multiple times for the NSX HOLs so that I could completely map out the HOL infrastructure (all subnets, all VLANs, all interfaces, interface types, etc..). Only then I was able to figure out how everything fit together. Before then, I just knew the steps to perform a DLR/ESG deployment and a basic OSPF setup.
Hope that helps.
