CKAD Application Design and Build Practice Question
You have a pod that runs a single container with the following resource limits: memory: 256Mi, cpu: 500m. The container is consistently using 300Mi of memory and 300m of CPU. The pod is running but you want to avoid OOMKilled. Which change should you make?
⚠ Common exam trap
A common mix-up: candidates confuse CPU and memory resource management, thinking that increasing CPU limits can solve memory-related OOM kills, or that requests alone (without adjusting limits) can prevent termination.
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
✓
Increase memory limit to 512Mi
The container is consistently using 300Mi of memory, which exceeds the current memory limit of 256Mi. When a container exceeds its memory limit, the kernel's OOM killer terminates the process (OOMKilled). Increasing the limit to 512Mi provides headroom above the actual usage, preventing OOM kills while allowing the container to continue running.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Increase memory limit to 512Mi
Why this is correct
The container is being OOMKilled because its memory usage exceeds the current limit, triggering the kernel OOM killer. Raising the limit to 512Mi provides sufficient headroom for the container's observed usage, allowing the process to continue running. This is only safe if the node has enough allocatable memory to accommodate the new limit.
- ✗
Set memory request to 128Mi and keep limit at 256Mi
Why it's wrong here
Setting a lower memory request does not alter the hard limit of 256Mi; the Linux cgroup memory limit still enforces that cap. If the container's actual memory footprint exceeds 256Mi, it will still be terminated by the OOM killer, regardless of the request value. Additionally, a lower request only affects scheduling and QoS class, not the runtime enforcement that caused the kill.
- ✗
Decrease memory limit to 128Mi
Why it's wrong here
Decreasing the memory limit to 128Mi tightens the cgroup constraint, so the container will cross the threshold even sooner and be OOMKilled faster. It does not cure the underlying problem of the process needing more memory; it simply moves the failure earlier. Since the container is clearly using more than 128Mi, this change guarantees continued or more frequent termination.
- ✗
Increase CPU limit to 1000m
Why it's wrong here
The OOMKilled status specifically indicates a memory-induced termination, not a CPU deficiency. CPU limits in Kubernetes cause throttling when exceeded, but they do not cause a process to be killed; only memory limit violations trigger the OOM killer. Therefore, increasing the CPU limit to 1000m will have no effect on the container's memory overcommitment and will not prevent its termination.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CKAD 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 CKAD exam.