This CKS practice question tests your understanding of system hardening. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. 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.
A security team wants to ensure that all containers in a pod run with only the minimum required Linux capabilities. Which of the following approaches is BEST?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Set securityContext.capabilities.drop: ['ALL'] with no add
Why wrong: Dropping all capabilities without adding any might cause the application to fail if it requires any capability. The best practice is to drop all and then add only required ones.
B
Leave capabilities unset to use the default set
Why wrong: Default capabilities are broad. This does not harden the system.
C
Add only the necessary capabilities without dropping
Why wrong: Adding capabilities without dropping increases the privilege set, contrary to hardening.
D
Set securityContext.capabilities.drop: ['ALL'] and add only necessary capabilities
Correct. Drop all default capabilities and add only those needed reduces the attack surface.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Set securityContext.capabilities.drop: ['ALL'] and add only necessary capabilities
Option D is correct because it implements the principle of least privilege by first dropping all capabilities with `drop: ['ALL']` and then explicitly adding back only those capabilities that are strictly necessary for the container to function. This ensures that the container runs with the absolute minimum set of Linux capabilities, reducing the attack surface and adhering to Kubernetes security best practices for system hardening.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Set securityContext.capabilities.drop: ['ALL'] with no add
Why it's wrong here
Dropping all capabilities without adding any might cause the application to fail if it requires any capability. The best practice is to drop all and then add only required ones.
✗
Leave capabilities unset to use the default set
Why it's wrong here
Default capabilities are broad. This does not harden the system.
✗
Add only the necessary capabilities without dropping
Why it's wrong here
Adding capabilities without dropping increases the privilege set, contrary to hardening.
✓
Set securityContext.capabilities.drop: ['ALL'] and add only necessary capabilities
Why this is correct
Correct. Drop all default capabilities and add only those needed reduces the attack surface.
Clue confirmation
The clue words "best", "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the misconception that simply dropping all capabilities is sufficient, but the trap here is that dropping all without adding necessary ones can break the application, while adding capabilities without dropping all leaves unnecessary capabilities enabled, both of which fail the 'minimum required' requirement.
Detailed technical explanation
How to think about this question
Under the hood, Linux capabilities are implemented as bitmasks in the kernel's task struct, and `securityContext.capabilities` in Kubernetes translates directly to the `cap_bset` and `cap_effective` sets via the `prctl` and `capset` syscalls. A common subtle behavior is that dropping `ALL` and then adding back capabilities is not the same as just adding capabilities; the former resets the bounding set to empty, preventing any inherited capabilities from being gained, while the latter leaves the bounding set at its default (which includes many capabilities). In a real-world scenario, a container running a web server might only need `NET_BIND_SERVICE` to bind to port 80, and dropping all others prevents an attacker from exploiting a vulnerability to use `CAP_SYS_ADMIN` or `CAP_NET_RAW` for further compromise.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKS question in full detail.
System Hardening — This question tests System Hardening — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Set securityContext.capabilities.drop: ['ALL'] and add only necessary capabilities — Option D is correct because it implements the principle of least privilege by first dropping all capabilities with `drop: ['ALL']` and then explicitly adding back only those capabilities that are strictly necessary for the container to function. This ensures that the container runs with the absolute minimum set of Linux capabilities, reducing the attack surface and adhering to Kubernetes security best practices for system hardening.
What should I do if I get this CKS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best", "minimum / minimize". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.