- A
The pod is trying to resolve 'db-service' without the namespace suffix
Pods in a different namespace must use 'db-service.data.svc.cluster.local'.
- B
The Service 'db-service' is not exposed on a port
Why wrong: The Service still has a DNS entry regardless of port.
- C
The pod's DNS policy is set to 'None'
Why wrong: DNS policy 'None' would prevent all DNS resolution.
- D
The pod's container image lacks DNS utilities
Why wrong: The kernel resolver handles DNS, not the image.
Question 677 of 997
Kubernetes DNS Cross-Namespace Service Resolution
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 pod named 'web-app' is not able to resolve the hostname 'db-service' from another namespace 'data'. The 'db-service' Service exists in the 'data' namespace. 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.
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 is trying to resolve 'db-service' without the namespace suffix
Option A is correct because, by default, Kubernetes DNS resolves service names only within the same namespace. To resolve a service from another namespace, the pod must use the fully qualified domain name (FQDN) in the format '<service>.<namespace>.svc.cluster.local'. Without the namespace suffix, the DNS query for 'db-service' fails because it is not found in the pod's own namespace.
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 is trying to resolve 'db-service' without the namespace suffix
Why this is correct
Pods in a different namespace must use 'db-service.data.svc.cluster.local'.
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.
- ✗
The Service 'db-service' is not exposed on a port
Why it's wrong here
The Service still has a DNS entry regardless of port.
- ✗
The pod's DNS policy is set to 'None'
Why it's wrong here
DNS policy 'None' would prevent all DNS resolution.
- ✗
The pod's container image lacks DNS utilities
Why it's wrong here
The kernel resolver handles DNS, not the image.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume Kubernetes DNS automatically resolves service names across all namespaces, similar to how a flat network would work, but in reality, DNS resolution is namespace-scoped unless the FQDN is used.
Detailed technical explanation
How to think about this question
Kubernetes DNS uses CoreDNS (or kube-dns in older clusters) to serve DNS records for Services and Pods. Each Service gets an A/AAAA record in the format '<service>.<namespace>.svc.cluster.local'. When a pod queries a short name like 'db-service', the DNS search domains (configured in /etc/resolv.conf) append the pod's own namespace and the cluster domain, so it resolves to 'db-service.<pod-namespace>.svc.cluster.local', not 'db-service.data.svc.cluster.local'. This behavior is defined in the DNS specification for Kubernetes (based on RFC 1035) and is a common source of cross-namespace connectivity issues.
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?
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 is trying to resolve 'db-service' without the namespace suffix — Option A is correct because, by default, Kubernetes DNS resolves service names only within the same namespace. To resolve a service from another namespace, the pod must use the fully qualified domain name (FQDN) in the format '<service>.<namespace>.svc.cluster.local'. Without the namespace suffix, the DNS query for 'db-service' fails because it is not found in the pod's own namespace.
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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