The correct answer combines `runAsNonRoot: true`, `runAsUser: 1000`, and `readOnlyRootFilesystem: true` within the pod and container SecurityContexts. This works because `runAsNonRoot` enforces that the container cannot run as UID 0, while `runAsUser: 1000` explicitly sets the user ID to satisfy the non-root requirement, and `readOnlyRootFilesystem: true` mounts the container’s filesystem as read-only, preventing any writes to the root layer. On the CKAD exam, this scenario tests your understanding of how pod-level versus container-level SecurityContext fields interact—a common trap is placing `readOnlyRootFilesystem` at the pod level, where it is ignored, or forgetting that `runAsNonRoot` alone does not set a specific UID. To remember, think “three locks for a secure container: no root, UID 1000, and a read-only disk.”
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.
A pod's container needs to run as non-root user with UID 1000 and ensure its filesystem is read-only. Which SecurityContext settings achieve this?
Option D is correct because it sets both `runAsNonRoot: true` (to enforce non-root execution) and `runAsUser: 1000` (to specify the exact UID) at the pod-level `securityContext`, while `readOnlyRootFilesystem: true` is set at the container-level `securityContext` to make the container's filesystem read-only. This combination satisfies the requirement of running as a non-root user with UID 1000 and ensuring a read-only root filesystem.
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.
This correctly sets non-root enforcement, UID, and read-only root filesystem.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse `runAsGroup` with `runAsUser` or forget that `runAsNonRoot` must be explicitly set to enforce non-root execution, assuming that setting a UID alone is sufficient.
Detailed technical explanation
How to think about this question
Under the hood, the `runAsNonRoot` field causes the kubelet to validate that the container's user ID is not 0 (root) before starting the container; if the UID is 0, the pod is rejected. The `readOnlyRootFilesystem` setting mounts the container's root filesystem as read-only, which prevents writes to the container layer but still allows writes to mounted volumes (e.g., emptyDir). A common real-world scenario is running a web server container that only serves static files, where a read-only root filesystem enhances security by preventing malware from modifying binaries or configuration.
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: securityContext:
runAsNonRoot: true
runAsUser: 1000
readOnlyRootFilesystem: true — Option D is correct because it sets both `runAsNonRoot: true` (to enforce non-root execution) and `runAsUser: 1000` (to specify the exact UID) at the pod-level `securityContext`, while `readOnlyRootFilesystem: true` is set at the container-level `securityContext` to make the container's filesystem read-only. This combination satisfies the requirement of running as a non-root user with UID 1000 and ensuring a read-only root filesystem.
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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Question Discussion
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