This KCNA practice question tests your understanding of container orchestration. 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 of the following is a container runtime that implements the Container Runtime Interface (CRI)?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
containerd
containerd is a high-level container runtime that directly implements the Container Runtime Interface (CRI) by exposing a gRPC API that kubelet can call to manage pods and containers. It was originally extracted from Docker and is now the default runtime in many Kubernetes distributions, providing image transfer, container lifecycle management, and storage/network attachment without requiring Docker as an intermediary.
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.
✓
containerd
Why this is correct
containerd is a high-level container runtime that implements the CRI and is used by Kubernetes.
Related concept
Read the scenario before looking for a memorised answer.
✗
Docker
Why it's wrong here
Docker is not natively CRI-compliant; Kubernetes deprecated Docker as a runtime after v1.24.
✗
runc
Why it's wrong here
runc is a low-level OCI runtime used by containerd, but it does not implement the CRI itself.
✗
kubelet
Why it's wrong here
The kubelet is the node agent that interacts with the container runtime via CRI, but it is not a runtime itself.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the misconception that Docker is a CRI-compliant runtime, when in fact Docker uses a separate adapter (dockershim) that was removed in Kubernetes v1.24, making containerd the standard CRI implementation.
Detailed technical explanation
How to think about this question
The CRI defines a gRPC-based protocol with two main services: RuntimeService (for pod sandbox and container lifecycle) and ImageService (for image management). containerd implements both services, and when kubelet sends a CRI request, containerd translates it into OCI-compliant operations using runc or other low-level runtimes. In production, containerd's shim process (containerd-shim) keeps the container's stdio streams alive even after the containerd daemon restarts, ensuring zero-downtime container supervision.
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 KCNA 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this KCNA question in full detail.
Container Orchestration — This question tests Container Orchestration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: containerd — containerd is a high-level container runtime that directly implements the Container Runtime Interface (CRI) by exposing a gRPC API that kubelet can call to manage pods and containers. It was originally extracted from Docker and is now the default runtime in many Kubernetes distributions, providing image transfer, container lifecycle management, and storage/network attachment without requiring Docker as an intermediary.
What should I do if I get this KCNA 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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