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Linux Foundation CKS Cheat Sheet: Hardening, Admission, and Runtime

April 24, 2026

Linux Foundation CKS cheat sheet for hardening, admission, runtime, traps, and final review.

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Use this cheat sheet for Certified Kubernetes Security Specialist (CKS) after you know the basics but before you start a timed practice block. The goal is not to memorize a vendor catalog; the goal is to classify the scenario and reject attractive wrong answers quickly.

CKS answer sequence

Use this when the stem mixes cluster access, workload hardening, image security, policy, or evidence.

    flowchart TD
	  S["Scenario"] --> L["Locate the security layer"]
	  L --> I["Check identity and RBAC"]
	  I --> W["Check workload, image, or network policy"]
	  W --> V["Verify containment, logs, or forensic evidence"]

First-pass question triage

  1. Name the tested lane before reading the answer choices.
  2. Underline the constraint: security, cost, reliability, latency, governance, implementation effort, or evidence.
  3. Reject answers that solve a neighboring problem but not the stated requirement.
  4. Prefer the smallest correct control, service, workflow, or command that satisfies the constraint.
  5. Look for proof: logs, tests, metrics, policy evidence, deployment status, evaluation results, or user-visible recovery.

What to know cold

Lane Decision rule Reject when
Cluster security model Understand API server, etcd, control plane, node, runtime, and workload security responsibilities. Protecting workloads while leaving cluster access or secrets exposed.
Identity and RBAC Use service accounts, roles, bindings, admission, and least privilege. Granting cluster-admin because an app needs one resource permission.
Workload and image security Apply pod security, admission controls, image scanning, signatures, secrets, and runtime restrictions. Trusting images or privileged pods by default.
Network and policy Use network policies, ingress control, service mesh options, and traffic isolation. Assuming service names imply isolation.
Monitoring and incident response Use audit logs, runtime signals, findings, containment, and forensic preservation. Deleting compromised resources before collecting evidence and scope.

Common traps and better instincts

Trap Better instinct
RBAC too broad Bind the smallest role to the right subject and namespace.
Secrets treated like config Protect secrets at rest, in transit, in manifests, and in logs.
No admission control Use policy to stop unsafe workloads before scheduling.
Network policy assumptions Verify plugin support, selectors, ingress, egress, and default behavior.

Final 15-minute review

If the stem says Start with
least privilege, private access, compliance, or audit identity scope, data boundary, policy enforcement, logging, and ownership
least operational effort managed service, native integration, simple workflow, and fewer moving parts
high availability, recovery, or outage failure domain, recovery objective, health check, rollback, and validation
performance, scale, or cost bottleneck evidence, traffic pattern, sizing, caching, batching, and quotas
troubleshoot, diagnose, or investigate symptom, recent change, logs, metrics, status, dependency, and smallest safe test

Practice fit

Use IT Mastery for the exact product route, practice status, spaced review when available, and close-answer explanation practice as coverage expands.

Open the exact IT Mastery route here: CKS on MasteryExamPrep.

Decision order

Cloud native security answers start with identity, policy, workload hardening, network isolation, audit evidence, and containment.

Revised on Sunday, May 10, 2026
Study Plan