- A
Drop all capabilities with capabilities.drop: ["ALL"]
Removes all capabilities, minimizing privilege.
- B
Add the SYS_ADMIN capability
Why wrong: Adding capabilities increases the attack surface.
- C
Set readOnlyRootFilesystem: true
Prevents writing to the root filesystem, limiting damage.
- D
Set runAsUser: 0
Why wrong: Running as root increases the attack surface.
- E
Set privileged: false
Why wrong: Privileged: false is the default; not setting it doesn't reduce attack surface beyond default.
Question 441 of 997
Reduce Container Attack Surface
This CKS practice question tests your understanding of minimize microservice vulnerabilities. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
Which TWO of the following are valid ways to reduce the attack surface of a container? (Select TWO)
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
✓
Drop all capabilities with capabilities.drop: ["ALL"]
Option A is correct because dropping all capabilities with `capabilities.drop: ["ALL"]` removes all Linux capabilities from the container, preventing it from performing privileged operations like raw socket access or mounting filesystems. This follows the principle of least privilege and directly reduces the attack surface by eliminating potential kernel-level exploits. Option C is correct because setting `readOnlyRootFilesystem: true` makes the container's root filesystem immutable at runtime, preventing attackers from writing malicious binaries or modifying configuration files even if they gain code execution inside the container.
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.
- ✓
Drop all capabilities with capabilities.drop: ["ALL"]
Why this is correct
Removes all capabilities, minimizing privilege.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Add the SYS_ADMIN capability
Why it's wrong here
Adding capabilities increases the attack surface.
- ✓
Set readOnlyRootFilesystem: true
Why this is correct
Prevents writing to the root filesystem, limiting damage.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Set runAsUser: 0
Why it's wrong here
Running as root increases the attack surface.
- ✗
Set privileged: false
Why it's wrong here
Privileged: false is the default; not setting it doesn't reduce attack surface beyond default.
Common exam traps
Common exam trap: answer the scenario, not the keyword
A common mistake in the CNCF CKS exam is thinking that `privileged: false` is an active security hardening measure, when in fact it is the default and does not reduce the attack surface beyond the baseline. The trap is that candidates select it thinking it disables privilege escalation, without realizing that dropping capabilities and setting readOnlyRootFilesystem are the actual active reductions.
Detailed technical explanation
How to think about this question
Under the hood, Linux capabilities are a granular set of privileges (e.g., CAP_NET_RAW, CAP_SYS_ADMIN) that are inherited from the container runtime. Dropping all capabilities with `capabilities.drop: ["ALL"]` leaves the container with zero capabilities, meaning even a `ping` command would fail unless the binary uses setuid or the `NET_RAW` capability is explicitly added. In a real-world scenario, a web application container that only serves static files can safely drop all capabilities and use a read-only root filesystem, preventing an attacker from installing a reverse shell or modifying `/etc/passwd` even if they exploit a vulnerability like Log4Shell.
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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Minimize Microservice Vulnerabilities — study guide chapter
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FAQ
Questions learners often ask
What does this CKS question test?
Minimize Microservice Vulnerabilities — This question tests Minimize Microservice Vulnerabilities — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Drop all capabilities with capabilities.drop: ["ALL"] — Option A is correct because dropping all capabilities with `capabilities.drop: ["ALL"]` removes all Linux capabilities from the container, preventing it from performing privileged operations like raw socket access or mounting filesystems. This follows the principle of least privilege and directly reduces the attack surface by eliminating potential kernel-level exploits. Option C is correct because setting `readOnlyRootFilesystem: true` makes the container's root filesystem immutable at runtime, preventing attackers from writing malicious binaries or modifying configuration files even if they gain code execution inside the container.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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 →
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Last reviewed: Jul 4, 2026
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.
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