- A
spec.containers[0].runtimeClassName: gvisor
Why wrong: runtimeClassName is at pod level, not container level.
- B
metadata.runtimeClassName: gvisor
Why wrong: runtimeClassName is in spec, not metadata.
- C
spec.runtimeClass: gvisor
Why wrong: The field is 'runtimeClassName', not 'runtimeClass'.
- D
spec.runtimeClassName: gvisor
Correct.
Question 982 of 997
gVisor Runtime Class in Kubernetes
This CKS practice question tests your understanding of minimize microservice vulnerabilities. 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 developer asks you to run a container with gVisor runtime. The cluster has a RuntimeClass named 'gvisor' defined. Which field must be added to the Pod spec to use gVisor?
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
✓
spec.runtimeClassName: gvisor
Option D is correct because the `runtimeClassName` field is a top-level field in the Pod spec (i.e., `spec.runtimeClassName`) that specifies the name of the RuntimeClass resource to use for running the Pod's containers. In this case, setting `spec.runtimeClassName: gvisor` instructs the kubelet to use the gVisor runtime (via the 'gvisor' RuntimeClass) for all containers in the Pod, enabling a sandboxed kernel for enhanced isolation.
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.
- ✗
spec.containers[0].runtimeClassName: gvisor
Why it's wrong here
runtimeClassName is at pod level, not container level.
- ✗
metadata.runtimeClassName: gvisor
Why it's wrong here
runtimeClassName is in spec, not metadata.
- ✗
spec.runtimeClass: gvisor
Why it's wrong here
The field is 'runtimeClassName', not 'runtimeClass'.
- ✓
spec.runtimeClassName: gvisor
Why this is correct
Correct.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The `runtimeClassName` field is a top-level field in the Pod spec (`spec.runtimeClassName`). A common mistake is setting it under `metadata` or `spec.containers[]`, or confusing it with the deprecated `runtimeClass` field. This question tests precise knowledge of the CNCF's Kubernetes API.
Detailed technical explanation
How to think about this question
The RuntimeClass resource defines a handler (e.g., 'runsc' for gVisor) that the container runtime uses to launch the container with a specific sandboxing technology. When `spec.runtimeClassName` is set, the kubelet selects the corresponding RuntimeClass, reads its handler, and passes it to the CRI (Container Runtime Interface) implementation, which then invokes the appropriate OCI-compatible runtime (like runsc for gVisor) instead of the default runc. This mechanism is critical in multi-tenant clusters where workloads require different isolation levels, and misconfiguring the field name can silently fall back to the default runtime, defeating the security purpose.
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 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. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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: spec.runtimeClassName: gvisor — Option D is correct because the `runtimeClassName` field is a top-level field in the Pod spec (i.e., `spec.runtimeClassName`) that specifies the name of the RuntimeClass resource to use for running the Pod's containers. In this case, setting `spec.runtimeClassName: gvisor` instructs the kubelet to use the gVisor runtime (via the 'gvisor' RuntimeClass) for all containers in the Pod, enabling a sandboxed kernel for enhanced isolation.
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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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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