- A
The Service type should be NodePort
Why wrong: Type ClusterIP works within the cluster.
- B
The pod is in a different namespace
Why wrong: Services only select pods in the same namespace.
- C
The pod's readiness probe is failing
Services only forward traffic to pods that pass readiness probes.
- D
The pod's container port is not defined
Why wrong: The Service targetPort must match the container port, but missing container port would not prevent traffic if targetPort matches.
Question 968 of 997
Why Is a Matching Pod Not Receiving Traffic from the Service?
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.
A user creates a Service of type ClusterIP with a selector matching pods labeled 'app: myapp'. However, a pod named 'myapp-pod' with label 'app: myapp' is not receiving traffic. What is a possible reason?
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 pod's readiness probe is failing
Option C is correct because a failing readiness probe causes the pod to be removed from the Service's Endpoints list, even if the pod is running and matches the selector. The kubelet checks the readiness probe periodically; if it fails, the pod is marked as not ready, and the Service controller removes its IP from the Endpoints object, preventing traffic from being forwarded to it.
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.
- ✗
The Service type should be NodePort
Why it's wrong here
Type ClusterIP works within the cluster.
- ✗
The pod is in a different namespace
Why it's wrong here
Services only select pods in the same namespace.
- ✓
The pod's readiness probe is failing
Why this is correct
Services only forward traffic to pods that pass readiness probes.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The pod's container port is not defined
Why it's wrong here
The Service targetPort must match the container port, but missing container port would not prevent traffic if targetPort matches.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The CNCF-KCNA exam often tests the distinction between liveness and readiness probes; the trap here is that candidates assume a running pod automatically receives traffic, overlooking that readiness probes explicitly gate traffic admission.
Detailed technical explanation
How to think about this question
Under the hood, the Service controller watches Endpoints objects, which are populated based on pods that match the selector and have all containers reporting ready (readiness probe passing). If a readiness probe fails, the pod's IP is removed from the Endpoints list, and the kube-proxy on each node updates iptables or IPVS rules to exclude that pod from the load-balancing set. In real-world scenarios, a common cause of readiness probe failure is a misconfigured HTTP endpoint that returns a non-2xx status code, causing the pod to be isolated from traffic without being restarted.
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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Container Orchestration — study guide chapter
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FAQ
Questions learners often ask
What does this KCNA question test?
Container Orchestration — This question tests Container Orchestration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The pod's readiness probe is failing — Option C is correct because a failing readiness probe causes the pod to be removed from the Service's Endpoints list, even if the pod is running and matches the selector. The kubelet checks the readiness probe periodically; if it fails, the pod is marked as not ready, and the Service controller removes its IP from the Endpoints object, preventing traffic from being forwarded to it.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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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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