Last week I took the CKAD exam. This is actually the first official certification I've ever done. I don't really need it for work, but I bought it when it was on discount last year. You have to take the exam within a year of purchasing it, so I naturally waited till the last minute to get it done.
To prepare for the exam, I watched this O'Reilly tutorial. I then performed all the exercises on my own cluster to make sure I was comfortable with everything. The other thing I tried to do was bookmark all the useful documentation pages on https://kubernetes.io/docs.
I would say 60% of the material were things that I'm very comfortable with and that I've been using for over a year. Pods, replica sets, deployements, etc. The rest were of things that I've heard of, but have not really needed to use in my day-to-day practice.
I scored 70%, with the minimum passing grade being 66%. I am not disappointed at all since my goal was to pass without putting too much extra effort.
The exam itself is done from home with remote proctoring. I found the proctoring to be a little too intrusive. You have to show the proctor your whole room by rotating the camera all around, under the table and all of that. Your desk also needs to be completely clean, and you can only use clear bottles for water. I had a cold on that day and I even had to show the contents of my package of tissues. I tend to put my hand over my mouth when I think, and I got scolded for doing that.
On the other hand, I guess that's the price you pay for the convenience of being able to take the exam from home.
All-in-all I enjoyed the experience of completing this exam. I was able to confirm my Kubernetes skills and fill in a few gaps that I'd been missing with a few days worth of preparation.