- A
The pod cannot resolve the DNS name because service DNS names are only resolvable within the same namespace
DNS resolution for services is namespace-scoped; you need to use the FQDN.
- B
Cross-namespace service access is not allowed by default
Why wrong: It is allowed, but the DNS name must include the namespace.
- C
The service has no endpoints
Why wrong: This would cause a different error, like connection refused.
- D
The service port is not correctly configured
Why wrong: This would cause issues even within the same namespace.
Question 68 of 997
Cross-Namespace Service DNS
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.
You create a Service of type ClusterIP in the 'default' namespace. You try to reach the Service from a pod in the 'production' namespace using the service name. The connection fails. What is the most likely reason?
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.
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 cannot resolve the DNS name because service DNS names are only resolvable within the same namespace
Option A is correct because, by default, Kubernetes DNS resolves Service names only within the same namespace. A Service named 'my-svc' in the 'default' namespace is resolvable as 'my-svc' only from pods in the 'default' namespace. From a pod in the 'production' namespace, the DNS name must be fully qualified as 'my-svc.default.svc.cluster.local' to be resolved, otherwise the DNS lookup fails, causing the connection to fail.
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 pod cannot resolve the DNS name because service DNS names are only resolvable within the same namespace
Why this is correct
DNS resolution for services is namespace-scoped; you need to use the FQDN.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Cross-namespace service access is not allowed by default
Why it's wrong here
It is allowed, but the DNS name must include the namespace.
- ✗
The service has no endpoints
Why it's wrong here
This would cause a different error, like connection refused.
- ✗
The service port is not correctly configured
Why it's wrong here
This would cause issues even within the same namespace.
Common exam traps
Common exam trap: answer the scenario, not the keyword
A common mistake is to think that Kubernetes network policies block cross-namespace traffic, but the actual issue is DNS name resolution. A Service DNS name is only resolvable within the same namespace unless a fully qualified domain name (FQDN) is used.
Detailed technical explanation
How to think about this question
Kubernetes DNS is implemented via CoreDNS, which appends the namespace and cluster domain (e.g., 'default.svc.cluster.local') to form fully qualified domain names (FQDNs). When a pod queries a short name like 'my-svc', CoreDNS searches only the pod's own namespace by default, following the DNS search path configured in /etc/resolv.conf (e.g., 'search production.svc.cluster.local svc.cluster.local cluster.local'). This behavior is defined by the ndots:5 setting and the search domains, which prioritize the local namespace. In real-world scenarios, multi-tenant clusters often rely on FQDNs or external DNS solutions to enable cross-namespace service discovery.
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.
Visual reference
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.
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FAQ
Questions learners often ask
What does this KCNA question test?
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 pod cannot resolve the DNS name because service DNS names are only resolvable within the same namespace — Option A is correct because, by default, Kubernetes DNS resolves Service names only within the same namespace. A Service named 'my-svc' in the 'default' namespace is resolvable as 'my-svc' only from pods in the 'default' namespace. From a pod in the 'production' namespace, the DNS name must be fully qualified as 'my-svc.default.svc.cluster.local' to be resolved, otherwise the DNS lookup fails, causing the connection to fail.
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: "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.
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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