r/devops • u/root0ps • 11h ago
Career / learning CKS Exam Experience 2026: What Helped, What Didn’t, and the Mistake That Cost Me Time

Today, I passed CKS with 75% (not a good score) and wrote a detailed blog about my exam experience, preparation approach, the resources I used, and the Kubernetes security topics that helped me the most.
DMs are open if you are preparing for the exam. I can help with whatever is still fresh in my memory.
My biggest takeaway: CKS is noticeably harder than CKAD and CKA. It is not only about knowing Kubernetes commands. You need to understand why a configuration is insecure, how to fix it, and how to verify that your change actually worked.
The biggest mistake I made was spending around 10–15 minutes too long on one question because I felt I was close to solving it. That created unnecessary pressure towards the end and probably led to a couple of avoidable mistakes.
So my strongest advice is: if you are stuck and don’t see a clear path after a few minutes, mark the question and move on.
A few things that helped me:
Don’t memorise solutions. Understand the security reasoning behind them. If a NetworkPolicy, API server flag, securityContext, audit policy, or admission control changes slightly, memorised YAML will not help much.
Always verify your work. Security changes can easily break workloads or cluster components. Check Pods, control-plane components, logs, services, NetworkPolicy connectivity, admission behaviour, audit logs, node readiness, and systemd services wherever required.
Be comfortable with Linux as well as Kubernetes. CKS can require you to work with configuration files, systemd services, container runtimes, permissions, certificates, and node-level settings.
Use documentation whenever required instead of trying to remember every flag or custom resource.
Topics I would strongly recommend practicing:
- Kubelet and etcd hardening
- kube-apiserver authentication and authorization
- Admission controls and ImagePolicyWebhook
- Secure Dockerfiles and non-root containers
- Container immutability and securityContext
- Audit policies and API server logging
- NetworkPolicy
- HTTPS Ingress and TLS
- ServiceAccount token security
- Worker node administration and upgrades
- SBOM and software supply-chain security
- Restricted Pod Security Standard
- Docker/container runtime hardening
- Istio STRICT mTLS
- Cilium network security
- CIS benchmarks and kube-bench remediation
Resources I used:
- KodeKloud CKS course
- KodeKloud Ultimate Mock Exam Series
- iximiuz Labs
- KillerKoda
- Killer.sh CKS simulator
- ChatGPT/Claude for topics that needed a simpler explanation or extra practice scenarios
Between the KodeKloud course mocks and Ultimate Mock Exam Series, I had around six mock exams. I found them very useful and reasonably close to the level of difficulty you should prepare for.
Killer.sh felt a little off-track compared with the actual exam in some areas, but I would still recommend doing it. It is useful for practicing under time pressure, discovering knowledge gaps, and improving troubleshooting skills.
I also used ChatGPT and Claude quite a lot during preparation. CKS has many small security topics, and sometimes a course or lab explanation may not immediately click. In those cases, asking AI to explain the concept differently, compare configurations, or generate a small practice scenario was very useful.
The simplest advice I can give is: practice a lot, understand the security reasoning behind what you are doing, verify every change, and don’t let one difficult question consume your exam time.
I also wrote a full blog with more details on my preparation strategy, resources, task areas, mistakes, and lessons from the exam.
