KCNA Container Orchestration Practice Question
A pod is running but its container exits with code 137. The pod logs show 'Killed'. What is the most likely cause?
⚠ Common exam trap
CNCF often tests the distinction between CPU throttling (which does not kill) and OOMKill (which does), and the trap here is that candidates confuse 'Killed' in logs with a generic failure, not recognizing exit code 137 as the specific OOMKill signal.
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 was OOMKilled due to memory limit
Exit code 137 (128 + 9) indicates the container was terminated by SIGKILL. Combined with 'Killed' in logs, this is the definitive signature of an OOMKill event, where the Linux kernel's Out-Of-Memory (OOM) killer terminates the container process because it exceeded its memory limit (specified in the pod's resource limits). Kubernetes enforces memory limits via cgroups, and when the container's memory usage surpasses the limit, the OOM killer sends SIGKILL, resulting in exit code 137.
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 container's CPU limit was exceeded
Why it's wrong here
Exceeding a CPU limit causes throttling, not termination; exit code 137 with 'Killed' indicates SIGKILL from memory exhaustion against the memory limit. CPU limits are the answer when a container runs slowly under load rather than being killed outright.
- ✗
The container's liveness probe failed
Why it's wrong here
Exit code 137 means SIGKILL, typically from the kernel OOM killer or an explicit kill, not a liveness probe failure, which restarts the container without that signal. Liveness probes are the answer when a container is unresponsive but still running, not when it is killed.
- ✓
The container was OOMKilled due to memory limit
Why this is correct
Exit code 137 equals 128 plus signal 9 (SIGKILL), which the kernel sends when a container exceeds its cgroup memory limit. The OOM killer terminates the process, producing the 'Killed' log entry rather than an application-level crash.
- ✗
The node ran out of disk space
Why it's wrong here
Node disk exhaustion triggers eviction with a DiskPressure condition and eviction messages, not a container-level SIGKILL producing exit code 137. Disk space is the answer when pods are evicted from a node or image pulls fail, not when a single container is killed.
Go deeper
Related to this question
About these practice questions
This KCNA question is part of Courseiva's 930-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.