- A
The pod is not running
Why wrong: The pod is running, so this is not the issue.
- B
The container does not have a shell binary
Correct. The container named 'app' exists, but it likely does not contain the /bin/sh binary, causing the exec to fail.
- C
The user does not have permission to exec into pods
Why wrong: Permission errors would result in a different error message, such as 'Forbidden'.
- D
The container name was not specified and the pod has multiple containers
Why wrong: The pod has only one container as stated, so container name ambiguity is not the issue.
Question 586 of 997
Kubectl Exec Container Not Found: Missing Shell Binary
This KCNA practice question tests your understanding of container orchestration. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: kubectl exec. 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 user runs 'kubectl exec -it pod1 -- /bin/sh' and gets an error: 'error: unable to upgrade connection: container not found'. The pod is running and has one container named 'app'. What is the most likely issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
✓
The container does not have a shell binary
The error 'unable to upgrade connection: container not found' can occur when the container image does not include the specified shell binary (/bin/sh). Although the container exists, kubectl cannot spawn a shell process because the binary is missing. Option D is incorrect because the pod has only one container (named 'app'), so the container name is unambiguous. Option A is incorrect because the pod is running. Option C is incorrect because permission errors produce a different message.
Key principle: kubectl exec
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The pod is not running
Why it's wrong here
The pod is running, so this is not the issue.
- ✓
The container does not have a shell binary
Why this is correct
Correct. The container named 'app' exists, but it likely does not contain the /bin/sh binary, causing the exec to fail.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
kubectl exec
- ✗
The user does not have permission to exec into pods
Why it's wrong here
Permission errors would result in a different error message, such as 'Forbidden'.
- ✗
The container name was not specified and the pod has multiple containers
Why it's wrong here
The pod has only one container as stated, so container name ambiguity is not the issue.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Candidates may misread the error and assume multiple containers, but the real issue is often a missing shell binary in minimal containers.
Detailed technical explanation
How to think about this question
Under the hood, kubectl exec uses the Kubernetes API's 'attach' or 'exec' subresource, which requires the container name to be passed as a query parameter. If the pod has multiple containers and none is specified, the API server returns an error because it cannot determine which container's process namespace to attach to. This is distinct from the 'kubectl exec' default behavior in single-container pods, where the container name is inferred automatically.
KKey Concepts to Remember
- kubectl exec
- Container not found error
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
kubectl exec
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. kubectl exec 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.
Review kubectl exec, then practise related KCNA questions on the same topic to reinforce the concept.
- →
Container Orchestration — study guide chapter
Learn the concepts, then practise the questions
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FAQ
Questions learners often ask
What does this KCNA question test?
Container Orchestration — This question tests Container Orchestration — kubectl exec.
What is the correct answer to this question?
The correct answer is: The container does not have a shell binary — The error 'unable to upgrade connection: container not found' can occur when the container image does not include the specified shell binary (/bin/sh). Although the container exists, kubectl cannot spawn a shell process because the binary is missing. Option D is incorrect because the pod has only one container (named 'app'), so the container name is unambiguous. Option A is incorrect because the pod is running. Option C is incorrect because permission errors produce a different message.
What should I do if I get this KCNA question wrong?
Review kubectl exec, then practise related KCNA questions on the same topic to reinforce the concept.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
kubectl exec
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Last reviewed: Jul 4, 2026
This KCNA 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 KCNA exam.
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