Question 68 of 997
System HardeningmediumMultiple ChoiceObjective-mapped

Cluster-Wide Capability Dropping — Mutating Admission Webhook vs PodSecurityPolicy | Certified Kubernetes Security Specialist Explained

This CKS practice question tests your understanding of system hardening. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. A key principle to apply: mutating Admission Webhook. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

During a security audit, it is found that containers running in a cluster have CAP_NET_RAW capability by default. The team wants to drop this capability for all containers. Which approach should be taken?

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

Use a mutating admission webhook to add a finalizer that drops capabilities

A mutating admission webhook can intercept Pod creation requests and modify the security context to drop capabilities like NET_RAW for all containers. This approach enforces the policy cluster-wide without requiring manual changes to each deployment, making it a viable alternative to deprecated PodSecurityPolicy.

Key principle: Mutating Admission Webhook

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Use a mutating admission webhook to add a finalizer that drops capabilities

    Why this is correct

    Correct. A mutating admission webhook can dynamically modify pods to drop the NET_RAW capability, ensuring cluster-wide enforcement without manual deployment updates.

    Related concept

    Mutating Admission Webhook

  • Create a PodSecurityPolicy with requiredDropCapabilities: [NET_RAW] and assign it to a role binding

    Why it's wrong here

    Incorrect. PodSecurityPolicy (PSP) is deprecated and removed in Kubernetes v1.25+. It should not be used in current clusters.

  • Configure kubelet with --allowed-unsafe-sysctls to restrict capabilities

    Why it's wrong here

    Incorrect. The kubelet flag --allowed-unsafe-sysctls is for sysctls, not for dropping capabilities.

  • Modify each deployment to include securityContext.capabilities.drop: [NET_RAW]

    Why it's wrong here

    Incorrect. While this works, it is not cluster-wide enforcement; it requires modifying each deployment individually, which is not scalable for all containers.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Candidates may incorrectly think that PodSecurityPolicy is still the standard mechanism, but it has been removed. A mutating admission webhook is a flexible and recommended approach for enforcing custom security constraints across the cluster.

Detailed technical explanation

How to think about this question

Capabilities in Linux are governed by the `capability.h` header and the `capget`/`capset` syscalls; dropping `CAP_NET_RAW` prevents a container from creating raw sockets (e.g., ICMP ping or ARP spoofing). PodSecurityPolicy works by injecting a `SecurityContext` into the pod spec during admission, which the container runtime (e.g., containerd) translates into the appropriate `cap_drop` entries in the OCI runtime spec. In real-world scenarios, dropping `NET_RAW` is critical for compliance with standards like PCI DSS, which require disabling raw socket access to prevent packet injection attacks.

KKey Concepts to Remember

  • Mutating Admission Webhook
  • Capability Drop

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Mutating Admission Webhook

Real-world example

How this comes up in practice

A practitioner preparing for the CKS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Mutating Admission Webhook Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.

What to study next

Got this wrong? Here's your next step.

Review mutating Admission Webhook, then practise related CKS questions on the same topic to reinforce the concept.

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FAQ

Questions learners often ask

What does this CKS question test?

System Hardening — This question tests System Hardening — Mutating Admission Webhook.

What is the correct answer to this question?

The correct answer is: Use a mutating admission webhook to add a finalizer that drops capabilities — A mutating admission webhook can intercept Pod creation requests and modify the security context to drop capabilities like NET_RAW for all containers. This approach enforces the policy cluster-wide without requiring manual changes to each deployment, making it a viable alternative to deprecated PodSecurityPolicy.

What should I do if I get this CKS question wrong?

Review mutating Admission Webhook, then practise related CKS questions on the same topic to reinforce the concept.

What is the key concept behind this question?

Mutating Admission Webhook

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Last reviewed: Jun 11, 2026

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This CKS practice question is part of Courseiva's free CNCF certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CKS exam.