CKA ClusterIP Service not reachable Practice Question
A ClusterIP Service is not reachable from within the cluster. You verify that the Service has endpoints. Which of the following could be the cause? (Select two.)
⚠ Common exam trap
Candidates may think a failing readiness probe can cause unreachability even when endpoints exist, but that is not possible because the pod would be removed from endpoints upon probe failure.
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
✓
kube-proxy is not running on the node.
Kube-proxy is responsible for implementing ClusterIP Service networking rules (iptables/IPVS) on each node; if it is not running, traffic to the Service's ClusterIP will not be forwarded to endpoints. Option B is correct because if the container is listening on a different port than the Service's targetPort, the connection will fail at the pod level. Option C is incorrect because a failing readiness probe would cause the pod to be removed from the Service's endpoints, contradicting the premise that the Service has endpoints. Option D is incorrect because service name length is not a factor for reachability (max is 63 characters).
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 pod's readiness probe is failing.
Why it's wrong here
A failing readiness probe would remove the pod from the Service's endpoint list, so the premise that endpoints exist would be false. Thus, this cannot be the cause when endpoints are present.
- ✗
The Service name is too long.
Why it's wrong here
Service name length does not affect connectivity.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The CKA exam frequently reuses these exact scenarios with slightly different constraints.
✓kube-proxy is not running on the node.Correct answer▾
✗The Service name is too long.Wrong answer — click to see why▾
Why this is wrong here
Service name length does not affect connectivity.
Analysis generated from the official CKAblueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CKA 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 CKA exam.