You find a lot of useful information on convo about the exam here
Certified Data Analyst Exam - Convo
I also wanted to add my opinion on it and how I found it. First of all, get ready to be annoyed a little bit. Registering and setting up your exam date is fairly easy. Then you receive a confirmation email, with useful information and requirements. This is what you have to care the most. Going through the system requirements is super important, make sure you check everything and tick every box.
On the day of the exam, you have to check-in not earlier than 30 minutes before the exam. Then a person will contact you and will check if the room you're in is as required. Your desk has to be completely empty, like completely. No pen, no paper, no nothing, including food, phone etc. They will ask you to take photos of the room you're in, also "showing them around" using your webcam.
This could be a bit stressful, a few of us had technical issues and actually skip the exam. Luckily, they could reschedule without losing all the money, but for that you have to contact customer service and explain the situation.
The good part is that the exam itself is not hard. I found it easier than the Alteryx Core Exam. If you go through the practice exam and revise for 2-4 hours, it shouldn't be a problem. Mind that we did it 2 weeks before the graduation. By this time most of us are familiar with basic calculations, parameter actions, filtering.
The second part of the 3 is a practical. You will work in Tableau for a number of really easy task, like build a pie chart with certain details or combine 2 sets etc.
Make sure you save your workbook!!
Lastly, don't worry if you fail, reschedule, revise and go at it again.
Good luck champ!