CKA Services and Networking Practice Question
A pod 'my-pod' in the 'default' namespace cannot resolve the service 'db-service' in the 'production' namespace. Which DNS name should be used to reach the service from 'my-pod'?
⚠ Common exam trap
Test-takers frequently assume the short service name works across namespaces or confuse the order of namespace and service in the FQDN, leading them to pick Option A or D, while Option C exploits the common misconception that pods use the same DNS suffix as services.
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
✓
db-service.production.svc.cluster.local
Kubernetes DNS resolves services across namespaces using the fully qualified domain name (FQDN) format `<service>.<namespace>.svc.cluster.local`. Since 'my-pod' is in the 'default' namespace and 'db-service' is in the 'production' namespace, the short name 'db-service' will not resolve; the FQDN must include the namespace and the cluster domain suffix to reach the service.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
db-service
Why it's wrong here
The unqualified name 'db-service' only resolves to a Service in the same namespace as the querying pod. Because the pod is in the default namespace, DNS search domains such as default.svc.cluster.local are appended, so 'db-service' becomes 'db-service.default.svc.cluster.local' — not the production Service. Without an explicit namespace, the production Service is completely unreachable via this short name.
- ✓
db-service.production.svc.cluster.local
Why this is correct
This is the fully qualified domain name (FQDN) for a Service in the production namespace, following the required Kubernetes DNS pattern: <service>.<namespace>.svc.<cluster-domain>. Since it is an absolute name with the 'svc' subdomain, it resolves to the ClusterIP of db-service regardless of the pod's namespace. The default cluster domain is 'cluster.local', so this name is valid and reachable from any namespace.
- ✗
db-service.production.pod.cluster.local
Why it's wrong here
The substring 'pod.cluster.local' indicates a Pod DNS name, not a Service DNS name. Kubernetes exposes Services under the 'svc.cluster.local' subdomain, while individual Pods have FQDNs like <hostname>.<namespace>.pod.cluster.local for headless Services or for Pods with hostNetwork. Using 'pod.cluster.local' for a Service will fail because no DNS record for 'db-service' exists in the 'production' namespace under that zone; Services are only registered under 'svc'.
- ✗
production.db-service.svc.cluster.local
Why it's wrong here
This reverses the DNS label order defined by Kubernetes. The canonical FQDN places the Service name first and the namespace second: <service>.<namespace>.svc.cluster.local. Here the name is parsed as a Service named 'production' in a namespace called 'db-service', which does not exist, so DNS resolution fails. The namespace must always follow the Service name in the FQDN, not precede it.
Visual reference
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Related to this question
Learn chapter
Services and Networking Fundamentals
Key term
CoreDNS
CoreDNS is a fast, flexible, and pluggable Domain Name System (DNS) server that is often used as the cluster DNS for Kubernetes, translating service names into IP addresses so containers can find each other.
Key term
Network Policies
A Kubernetes resource that controls how pods communicate with each other and with other network endpoints, acting as a firewall for pod-to-pod traffic.
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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.