Honestly, there is no fastest way to pass CCNA RS 200-125 exam. You can make the preparation best. It depends on you. All you have to do is the regular target achievement. You have to fix different targets every day. It means if you determine to pass the exam at the first trial then you must start taking preparation from the very first day.
You can find many guideline providers online or in your local area. If possible, you can take a look at their activities. If you think their activities are okay to follow up then do not be late. In the case of the economy, you can take preparation at home arranging the same materials at your home.
The best and fastest way to pass CCNA RS 200-125 is to have a plan. You have to go through the plan. Your plan should have all the necessary information and details about the subjects.