KCNA Cloud Native Application Delivery Practice Question
This KCNA practice question tests your understanding of cloud native application delivery. 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.
A financial services company runs a critical trading application on Kubernetes. The application is deployed as a Deployment with 3 replicas. Each pod exposes metrics on port 8080 and uses a ConfigMap to load configuration. Recently, after a configuration change via a ConfigMap update, two of the three pods started crashing with an out-of-memory (OOM) error, while the third pod continues to run fine. The team verified that the ConfigMap was updated correctly and that the application code did not change. The pods have resource limits set: memory limit of 512Mi and request of 256Mi. The application's memory usage before the change was around 200Mi. The new configuration increases the in-memory cache size. The team suspects the issue is related to the configuration change. What is the best course of action?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Increase the memory limit in the Deployment manifest to a higher value, such as 1Gi, and perform a rolling update.
Option D is correct because the OOM errors are directly caused by the increased memory usage from the larger in-memory cache, which exceeds the current 512Mi memory limit. Increasing the limit to 1Gi accommodates the new cache size while preserving resource boundaries, and a rolling update applies the change without downtime. This aligns with Kubernetes best practices of setting realistic resource limits based on application requirements.
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.
✗
Scale the Deployment to 5 replicas to distribute the memory load.
Why it's wrong here
More replicas increase total memory usage; does not fix per-pod OOM.
✗
Remove the memory limit from the container spec to allow unlimited memory usage.
Why it's wrong here
Removing limits can cause nodes to run out of memory and affect other workloads.
✗
Revert the ConfigMap to the previous configuration and monitor memory usage.
Why it's wrong here
This avoids the issue but does not allow the new cache feature; not a long-term solution.
✓
Increase the memory limit in the Deployment manifest to a higher value, such as 1Gi, and perform a rolling update.
Why this is correct
This directly addresses the OOM caused by increased cache size.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the misconception that scaling replicas or removing limits solves resource exhaustion, when the correct approach is to adjust resource limits to match the application's new requirements.
Detailed technical explanation
How to think about this question
Kubernetes enforces memory limits via cgroups; when a pod exceeds its limit, the OOM killer terminates the container. The application's memory usage jumped from ~200Mi to over 512Mi due to the cache increase, causing two pods to crash while the third survived possibly due to slightly lower cache population or GC timing. A rolling update with the new limit ensures the Deployment's desired state is updated without manual intervention, and the controller handles the gradual replacement of pods.
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.
Cloud Native Application Delivery — This question tests Cloud Native Application Delivery — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Increase the memory limit in the Deployment manifest to a higher value, such as 1Gi, and perform a rolling update. — Option D is correct because the OOM errors are directly caused by the increased memory usage from the larger in-memory cache, which exceeds the current 512Mi memory limit. Increasing the limit to 1Gi accommodates the new cache size while preserving resource boundaries, and a rolling update applies the change without downtime. This aligns with Kubernetes best practices of setting realistic resource limits based on application requirements.
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.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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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