CKAD Practice Question: Application Environment, Configuration and Security
This CKAD practice question tests your understanding of application environment, configuration and security. 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.
Which two fields can be used in a SecurityContext to control a container's access to the host filesystem? (Choose two.)
Why wrong: This sets the user ID but does not directly control filesystem access.
B
capabilities
Why wrong: Capabilities like CAP_SYS_ADMIN can affect filesystem access, but the question asks for fields that control access; capabilities are not a field that directly controls filesystem access in the same way.
C
readOnlyRootFilesystem
When set to true, the container's root filesystem is read-only, preventing writes.
D
allowPrivilegeEscalation
When set to false, processes in the container cannot gain more privileges, which restricts filesystem access.
E
runAsGroup
Why wrong: This sets the group ID but does not directly control filesystem access.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
readOnlyRootFilesystem
Option C is correct because setting `readOnlyRootFilesystem: true` in a container's SecurityContext mounts the container's root filesystem as read-only, preventing any writes to the host filesystem through the container's root. This directly controls access to the host filesystem by blocking modifications. Option D is correct because `allowPrivilegeEscalation: false` prevents a process from gaining more privileges than its parent, which restricts the ability to perform privileged operations that could access the host filesystem, such as mounting or modifying host paths.
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.
✗
runAsUser
Why it's wrong here
This sets the user ID but does not directly control filesystem access.
✗
capabilities
Why it's wrong here
Capabilities like CAP_SYS_ADMIN can affect filesystem access, but the question asks for fields that control access; capabilities are not a field that directly controls filesystem access in the same way.
✓
readOnlyRootFilesystem
Why this is correct
When set to true, the container's root filesystem is read-only, preventing writes.
Related concept
Read the scenario before looking for a memorised answer.
✓
allowPrivilegeEscalation
Why this is correct
When set to false, processes in the container cannot gain more privileges, which restricts filesystem access.
Related concept
Read the scenario before looking for a memorised answer.
✗
runAsGroup
Why it's wrong here
This sets the group ID but does not directly control filesystem access.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the distinction between fields that control user identity (runAsUser, runAsGroup) versus fields that directly restrict filesystem access or privilege escalation, leading candidates to mistakenly select identity fields as filesystem access controls.
Detailed technical explanation
How to think about this question
Under the hood, `readOnlyRootFilesystem` leverages the Linux kernel's mount namespace and the MS_RDONLY flag to enforce a read-only mount on the container's root filesystem, preventing any writes even by the root user. `allowPrivilegeEscalation` controls the `no_new_privs` flag in the kernel, which blocks the `setuid` bit and other privilege-gaining mechanisms, effectively preventing a container from escalating to root or performing privileged syscalls that could access host filesystems. In real-world scenarios, combining these two fields is a common security hardening practice to mitigate container breakout attacks, such as those exploiting writable `/proc` or `/sys` mounts.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKAD question in full detail.
Application Environment, Configuration and Security — This question tests Application Environment, Configuration and Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: readOnlyRootFilesystem — Option C is correct because setting `readOnlyRootFilesystem: true` in a container's SecurityContext mounts the container's root filesystem as read-only, preventing any writes to the host filesystem through the container's root. This directly controls access to the host filesystem by blocking modifications. Option D is correct because `allowPrivilegeEscalation: false` prevents a process from gaining more privileges than its parent, which restricts the ability to perform privileged operations that could access the host filesystem, such as mounting or modifying host paths.
What should I do if I get this CKAD 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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