This KCNA practice question tests your understanding of kubernetes fundamentals. 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 developer creates a Service of type ClusterIP in namespace 'default'. They attempt to reach the Service from another pod in the same namespace using the Service name 'my-svc'. The connection fails. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
The Service port does not match the container port
Why wrong: If ports don't match, the connection would reach the service but fail at the container; however, the symptom would be connection refused, not DNS failure.
B
The cluster DNS service (CoreDNS) is not running or misconfigured
DNS is required for Service name resolution.
C
The Service type should be NodePort
Why wrong: NodePort is for external access; internal access works with ClusterIP.
D
The Service selector does not match any pod labels
Why wrong: If selectors don't match, the Service has no endpoints, but the connection might still reach an empty set.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The cluster DNS service (CoreDNS) is not running or misconfigured
ClusterIP Services are only accessible within the cluster via DNS. If DNS resolution is not working, the pod cannot resolve the Service name.
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 port does not match the container port
Why it's wrong here
If ports don't match, the connection would reach the service but fail at the container; however, the symptom would be connection refused, not DNS failure.
✓
The cluster DNS service (CoreDNS) is not running or misconfigured
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The Service type should be NodePort
Why it's wrong here
NodePort is for external access; internal access works with ClusterIP.
✗
The Service selector does not match any pod labels
Why it's wrong here
If selectors don't match, the Service has no endpoints, but the connection might still reach an empty set.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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.
Identify which KCNA exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Kubernetes Fundamentals — This question tests Kubernetes Fundamentals — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The cluster DNS service (CoreDNS) is not running or misconfigured — ClusterIP Services are only accessible within the cluster via DNS. If DNS resolution is not working, the pod cannot resolve the Service name.
What should I do if I get this KCNA question wrong?
Identify which KCNA exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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