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. 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.
An administrator runs 'kubectl get pods' and sees that a pod named 'app-pod' is in 'CrashLoopBackOff'. They run 'kubectl logs app-pod' and see a segmentation fault error. What is the most likely cause?
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.
The node is out of memory
Why wrong: Out of memory causes OOMKill, not segmentation fault.
The container has a configuration error
Why wrong: Configuration errors may cause crashes, but segfault usually indicates a code bug.
The application code has a bug
Segmentation faults are typically caused by bugs in the application code.
The readiness probe is misconfigured
Why wrong: Readiness probe failure does not crash the container.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The application code has a bug
A segmentation fault (segfault) is a specific error caused by a program attempting to access memory it does not have permission to access, typically due to a bug in the application code (e.g., null pointer dereference, buffer overflow). Since the container starts but then crashes repeatedly (CrashLoopBackOff), the segfault indicates the application itself is failing, not the infrastructure or configuration. This is the most direct cause of the pod entering CrashLoopBackOff.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
The node is out of memory
Why it's wrong here
Out of memory causes OOMKill, not segmentation fault.
The container has a configuration error
Why it's wrong here
Configuration errors may cause crashes, but segfault usually indicates a code bug.
The application code has a bug
Why this is correct
Segmentation faults are typically caused by bugs in the application code.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
The readiness probe is misconfigured
Why it's wrong here
Readiness probe failure does not crash the container.
Common exam traps
CNCF often tests the distinction between application-level errors (like segfaults) and infrastructure or configuration issues, tempting candidates to blame resource constraints or probe misconfiguration when the logs clearly point to a runtime crash.
Detailed technical explanation
A segmentation fault occurs when a process attempts to access a memory address that is not mapped in its virtual address space, often due to programming errors like dereferencing a null pointer or writing past the end of a buffer. In Kubernetes, the kubelet monitors container processes via the container runtime (e.g., containerd); when the process exits with a signal like SIGSEGV (signal 11), the kubelet restarts the container, leading to CrashLoopBackOff. Real-world scenarios include applications compiled with memory safety issues in C/C++ or Go code that panics due to nil pointer dereference.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
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FAQ
Container Orchestration — This question tests Container Orchestration — Read the scenario before looking for a memorised answer..
The correct answer is: The application code has a bug — A segmentation fault (segfault) is a specific error caused by a program attempting to access memory it does not have permission to access, typically due to a bug in the application code (e.g., null pointer dereference, buffer overflow). Since the container starts but then crashes repeatedly (CrashLoopBackOff), the segfault indicates the application itself is failing, not the infrastructure or configuration. This is the most direct cause of the pod entering CrashLoopBackOff.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 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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