Kubernetes
Deploy, scale, break and repair a real single-node cluster.
31 labs and exams
Pass your CNCF certification on a real cluster
Practice exams timed and weighted like the paper you are booking, on a live Kubernetes cluster in a browser tab. Every task is graded against actual cluster state, so a pass means you did the work.
No card. Every lab is free.
Demo shell
Cluster ready
session 00:00
Incident · P1
web-frontend is down
Monitoring paged at 09:12. The web Service stopped answering and it was healthy at 09:00 — something changed the cluster. No steps. Find it.
SLO99.5% availability — burning
Still down
The web Service has no endpoints. Nothing is answering on port 80.
The web Service has no endpoints. Nothing is answering on port 80.
learner@lab:~$ curl -s http://10.43.20.14/ curl: (7) Failed to connect to 10.43.20.14 port 80: Connection refused learner@lab:~$ kubectl get pods -l app=web NAME READY STATUS RESTARTS AGE web-6f8d9c4b7-4mzql 1/1 Running 0 14m web-6f8d9c4b7-t8kxr 1/1 Running 0 14m learner@lab:~$ kubectl get endpoints web NAME ENDPOINTS AGE web <none> 14m learner@lab:~$
Catalogue
The stacks the exams are built on
Every one of these has labs in the catalogue today.
Linux
Files, permissions, services and the shell they all live in.
1 labs and exams
Docker
A real daemon: build an image, run it, compose a stack.
1 labs and exams
Istio
A live mesh: traffic shifting, mTLS and what breaks under both.
1 labs and exams
Argo
Workflows, CD, Rollouts and Events on a running cluster.
2 labs and exams
Cilium
Network policy and eBPF, on a cluster you can watch drop packets.
1 labs and exams
Prometheus
Run it, scrape a target, and answer a question in PromQL.
1 labs and exams
How it works
How it works
-
Start a lab
A container boots on our infrastructure with a real kernel, a real package manager and, where the lab needs one, a real single-node Kubernetes cluster. Nothing installs on your machine.
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Do the work in a terminal
A full shell in the browser tab. The same commands you would run on a server — kubectl, docker, systemctl, ip, journalctl — against a system that behaves like a server, because it is one.
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Get checked, not marked
Validation runs a script inside the machine and inspects what is actually there: the running pods, the file's permissions, the listening port. There is no answer to recognise and nothing to tick.
Four modes
Four ways to work, one engine
The same sandboxes and the same validation underneath all of them, so a pass means the same thing everywhere.
Break/fix incidents
The system boots broken. You get an incident report, a clock, and no instructions.
The fault is different for each person, so a solution posted online will not run on your cluster.
The only way through is to actually diagnose it — read the logs, form a hypothesis, test it, and fix the thing that is really wrong.
Guided labs
Instructions beside a live terminal. You run real commands on a real machine, and each step is verified against system state before you move on.
Exams
Timed and weighted like the certification they mirror, then scored per domain — a pass tells you you are ready, and a fail tells you which subject to go back to.
Ranked races
Two people, identical broken environments, first correct fix wins. The same validation as everything else, so speed never beats a fix that does not hold.
After an exam
What you get after an exam
Not a number. A breakdown by domain, weighted the way the real exam weights it, so you know which subject cost you the pass.
Example report
Illustrative figures — this is the shape of the report, not anyone's result.
Not ready yet — Storage and troubleshooting are below the line. Those are the two to work on before you book the real exam.
- Troubleshooting30% weight
- 42%
- Cluster architecture25% weight
- 81%
- Services and networking20% weight
- 74%
- Workloads and scheduling15% weight
- 88%
- Storage10% weight
- 40%
Catalogue
What is in the catalogue
Practice exams for the CNCF certifications, and the free labs that get you ready for them. Every lab is free to run; exams are sold separately.
Labs
- dockerIncident: the storefront stack is half up
- kubernetesIncident: the batch workers will not schedule
- kubernetesIncident: the records data tier is offline
- kubernetesIncident: the frontend cannot reach the API
- kubernetesIncident: shop.example.dz is unreachable from outside
- kubernetesIncident: the deploy bot is locked out
- kubernetesIncident: web-frontend is down
- linuxIncident: the web server on app-01 is not serving
Certification practice
- 60 questionsCAPA Practice Exam 1
- 60 questionsCBA Practice Exam 1
- 60 questionsCCA Practice Exam 1
- 60 questionsCGOA Practice Exam 1
- 17 tasksCKA Simulator B
- 15 tasksCKA Simulator C
- 17 tasksCKA Practice Exam 1
- 17 tasksCKA Practice Exam 2
- 17 tasksCKA Mock Exam — exam day
- 23 tasksCKA Final Exam
- 17 tasksCKAD Practice Exam 1
- 17 tasksCKAD Practice Exam 2
- 17 tasksCKAD Mock Exam — exam day
- 17 tasksCKNE Practice Exam 1
- 17 tasksCKNE Practice Exam 2
- 17 tasksCKNE Mock Exam — exam day
- 17 tasksCKNE Practice Exam 4
- 17 tasksCKNE Practice Exam 5
- 17 tasksCKS Practice Exam 1
- 17 tasksCKS Practice Exam 2
- 17 tasksCKS Mock Exam — exam day
- 60 questionsCNPA Practice Exam 1
- 17 tasksICA Practice Exam 1
- 60 questionsKCA Practice Exam 1
- 60 questionsKCNA Practice Exam 1
- 60 questionsKCNA Practice Exam 2
- 60 questionsKCNA Practice Exam 3
- 60 questionsKCSA Practice Exam 1
- 60 questionsKCSA Practice Exam 2
- 60 questionsKCSA Practice Exam 3
- 60 questionsOTCA Practice Exam 1
- 60 questionsPCA Practice Exam 1
Pricing
Pricing
Free — no card
$0
Every lab in the catalogue. One session at a time. One free readiness check per hands-on exam, which grades a sample of real tasks and reports where you are weak.
Written exam
$0
60 questions, 90 minutes, every answer explained in the review.
Hands-on exam
$10$30
17 timed tasks on a live cluster, scored per domain.
Written papers are free, with no card and no expiry. A hands-on exam lasts 365 days from purchase, with unlimited retakes — the sandbox is rebuilt from scratch each attempt.
Charged in US dollars by international card — Visa or Mastercard — through Stripe. Access opens the moment the payment clears; your bank sets the exchange rate it applies.
FAQ
Questions
Is this a real environment or a simulation?
Real. Each session is a Linux container on our infrastructure with its own filesystem, processes and network. Labs that need Kubernetes run a real single-node k3s cluster inside it, and the Docker labs run a real Docker daemon. You can break it, and you often are meant to.
Do I have to install anything?
No. The terminal is a browser tab. Nothing is installed on your machine and nothing is left behind when the session ends.
Killer.sh comes free with my CNCF exam registration. Why pay for this?
Killer.sh gives you two sessions. Here, an exam entitlement lasts a year and you can retake as often as you like — the sandbox is rebuilt from scratch each time, so it is a real attempt rather than a replay.
You also get two things it does not have: break/fix incidents where the fault differs per person, so a posted walkthrough will not work on your environment, and a per-domain readiness report rather than a single number — it names the subject you are weak in instead of leaving you to guess.
If you already have Killer.sh, use it. It is good and it is already paid for. Come here for the retries and for knowing why you failed.
What do I need to run it?
A current browser and a working connection. The terminal is text over a websocket, so it stays usable on a slow line — there is no video and no remote desktop. A physical keyboard makes the exams far easier than a phone.
How do I pay, and what do I get for it?
An international card — Visa or Mastercard — charged in US dollars through Stripe. One payment per certification, not a subscription: it opens that certification's hands-on exams for 365 days with unlimited retakes. Written papers, incident labs and races are free and need no card at all.
Know whether you are ready before you book
Every hands-on exam has one free readiness check: a sample of its real tasks, graded on cluster state and reported per domain. No card, and it names the subject you are short on rather than a number.