I studied only by looking at this. I studied for a week and passed with a score of 810. There were cases where the practice problems and the test problems were exactly the same. Since the scope is large, the lecture does not cover all the scopes (I remember things like the aws carbon footprint). However, except for a few problems, you can solve the problems sufficiently by elimination. CLF-C01 (current version) will expire on September 18th of this year, and the exam will be reorganized into a new version after that. Please note this.