The moment I logged into the exam and read the first question, I felt a rush of adrenaline — a mix of excitement and anxiety that I was not prepared for.

Introduction

Since all of the ideas are still fresh in my mind after getting my Certified Kubernetes Security Specialist (CKS) certification recently, I wanted to create a quick debriefing for myself and maybe someone else who is looking for some guidance on the exam. You will not find any answers to questions on the exam here, these are just my thoughts and at most they will nudge you in the right direction. We will discuss my preparation, the exam attempts themselves, the hurdles, lessons learned and key take-aways. At the end I will share a list of resources I used to prepare for the exam. In part 2 of this series we will get a bit more technical and discuss some very important details that will make or break your exam, as well as knowledge you’ll gain by going for this certification.

The preparation

Prerequisite: Certified Kubernetes Administrator (CKA)

Before attempting the CKS, the student should first pass their Certified Kubernetes Administrator (CKA) exam. That is what I did in January of this year. Most of the content covered in this prerequisite certification was known through my research and experience during my job as an Azure platform engineer maintaining AKS clusters at my clients. Yet, there were some unfamiliar topics.

The first step in my studies was buying Mumshad’s CKA course on Udemy which came with a large set of exercises on his KodeKloud platform. Such a great resource, and a very interactive way of learning. As these exams are hands-on, practical experience is absolutely key. With all of the hands-on exams (CKAD, CKA, CKS) there will be two session on an exam simulator provided to you. These are available on the Killer.Sh platform, and they are (for the CKA at least) comparable in difficulty to the actual exam.

My recommended approach, and the approach I personally took, is to study with KodeKloud until you can efficiently solve all exercises. Then, move on to your first set of the Killer.Sh exam simulator questions. Act as if this is a real exam, to get the best result possible to be able to judge your current knowledge. Continue to study topics that you score poorly on, learn from the Killer.Sh answers as well. Try to complete all Killercoda exercises as fast as possible to increase your efficiency.

Using this method I scored 89%, passing the exam on my first attempt.

CKS: Certified Kubernetes Security Specialist

Feeling confident after the successful exam, I set my eyes on CKS and used the same method as before.

  • Killer.Sh free course on youtube
  • KodeKloud course with exercises
  • Killercoda free exercises
  • Killer.Sh exam simulator included in the certification price

The Exam

First Attempt

Like all other proctored hands-on exams offered by the Linux Foundation, you check in 30 minutes before the start of the exam to verify your identity and make sure that your room is secure. Then, we’re off. You’ll get 15–20 questions, 120 minutes and a crappy virtual desktop connection.

Unlike the CKA, this exam was incredibly hard. I studied a lot, did loads of exercises, had scored very well on the practice exams but I was not at all prepared enough to ace the exam. It became a race against the clock, stress started to set in and I ended up scoring a 57%. As the passing grade is 67%, this was not enough. Going into the exam I felt quite confident, but not so much afterwards. Even thought the score was quite close, it did not feel close at all. There was a lot more to learn. Some of these questions blind-sided me. The practice exams for the CKA were very similar in difficulty compared to the real exam, but that was not the case for here. I had the feeling that I knew the answer to the question, but did not have all the necessary skills to perform it fully like they asked me to.

For example: throughout your studies you will learn from courses and the documentation itself that the Docker daemon.json file located at /etc/docker or .config/docker is used to secure the Docker socket. You would expect a json file in one of these locations during the exam, but no not the case. Creating the file yourself achieves nothing because it is not used. More about this in the upcoming blog. This exam is just full of these unexpected scenarios.

Lessons Learned

This is where I made a big mistake. Instead of immediately making an appointment for my next exam session, I put if off for another time. Something that in the end cost me quite a lot. The idea was to take the time to dig deep into the questions that I found the hardest or I didn’t understand fully. While this might sound logical, it opens up the door to endlessly kick the can down the road. There will always be something that you can explore further, but in this case it started a bit of a tunnel vision which then caused some deterioration on my other topics. I didn’t do much exercises and focussed mostly on theory. Not good..

After a little over a month I finally decided to retake the exam. It went a lot smoother, but still some tough questions. The feeling I got was better than the previous attempt, but still unsure as to wether I passed or not. Results came in 24 hours after the exam and I scored 66%. This missed the passing grade of 67% by 1 point and well.. made me open my wallet again… Each certification comes with 2 attempts, of which I failed both now.

Third Time’s the Charm

Instead of putting it off for a whole month, this time I immediately booked a new exam attempt a few days after the previous one. It gave me a hard deadline that was coming up soon, which motivated me to move quickly.

Instead of completing more exercises or practice exams I started drilling deeper into the specifics of the though questions. During the exam you can freely use the documentation of some of the tools used in the exam and Kubernetes itself. However, you do not have any time to be scanning these documentation pages for the right answer. You need to know what to do, where it is documented and then use the documentation efficiently to implement the solution.

Without getting too technical, the exam requires you to use some very specific features of tools like Falco, Cilium, and even Linux that might not be covered during your training, exercises, etc. I will go into more detail soon with a post more closely related to the content of the exam itself.

After gaining some important technical insights I spun up an Azure VM again and started messing around with the tools. This ended op helping me an incredible amount. Because of this, my third attempt ended up being a pass with a score of 90% and I can now proudly say that I’m a Certified Kubernetes Security Specialist.

The Mental Aspect

Wow, did I underestimate how important this was. There were so many times during the study, preparation, the exam itself and even the grading period after the exam where I started to doubt; myself, what I was doing and if this was ever going to work. During the first attempt stress started to set in immediately after the first question, when the realisation came that it was going to be an incredibly difficult exam. Mental preparation is such an important factor in performing well in these exams. You can’t start doubting yourself and your answers because you’ll loose so much time.

The two failed attempts really helped me learn not to let the outcome influence my mental state. That was especially difficult after missing out by 1%. I studied hard and gave it my all. If it wasn’t good enough then I did not meet the requirements for the certification. In the end this helped me a lot, accepting that failure is just a learning opportunity.

Conclusion

These are some important notes that helped me along the way:

  1. Be prepared to fail
  • Passing this exam on your first attempt would be phenomenal, but an unrealistic expectation. The exam is very hard and you should get back to it right away after failing. Don’t postpone, don’t procrastinate. Book your second attempt at most a few weeks after you failed the previous.
  1. The real exam is a lot harder than the practice exams
  • Unlike the CKA where the practice exams are on the same level as the real exams, that’s not the case for the CKS. We’ll discuss in more detail in part 2, but the questions required a lot more knowledge and were very easy to make mistakes on.
  1. Move on
  • There are 15–20 questions. No time to waste. If the you get stuck, you have to move on to the next question. Flag it to return after you finished the other ones, but expect to not finish it at all. Don’t spend time on details.
  1. Hands-on practice
  • Spin up some virtual machines, and create a cluster out of them. Maybe even use some old hardware that is available to you. But don’t solely rely on third-party’s. Go through the documentation of the tools yourself and try to master the concepts by implementing them on your own cluster. A course or youtube video doesn’t cover everything.
  1. Confidence
  • Make sure to believe in your own abilities. Confidence during the exam will help you so much. On-the-spot problem solving and debugging skills will matter a lot during this exam. These will be impacted a lot when you’re in a negative frame of mind.

In summary, this certification really pushed my mental en technical abilities. Be prepared, be confident and most importantly keep going until you succeed. It is totally worth it in the end. So many lessons learned.

Resources

A small list of resources I’ve used to prepare for the exam.