CKA Services and Networking Practice Question
What is the DNS name for a Service named 'api' in the 'default' namespace?
⚠ Common exam trap
The trap here is that candidates often forget the `svc` subdomain or reverse the service/namespace order, because they may confuse the DNS format with other Kubernetes naming conventions (e.g., pod DNS or headless service records) or assume the namespace comes first.
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
✓
api.default.svc.cluster.local
The correct DNS name for a Service in Kubernetes follows the pattern `<service-name>.<namespace>.svc.cluster.local`. For a Service named 'api' in the 'default' namespace, this resolves to `api.default.svc.cluster.local`. The `svc` subdomain is a fixed part of the cluster domain, and `cluster.local` is the default cluster domain suffix configured in kubelet and CoreDNS.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
api.default.svc.cluster.local
Why this is correct
The Kubernetes DNS schema for a Service is <service-name>.<namespace>.svc.cluster.local. Since the Service is named 'api' and created in the default namespace, the fully qualified domain name becomes api.default.svc.cluster.local. This FQDN resolves to the Service's ClusterIP and enables reliable cluster-wide service discovery.
- ✗
default.api.svc.cluster.local
Why it's wrong here
This reverses the expected resource and namespace ordering. In Kubernetes, the Service name is the leftmost label, followed by the namespace, so the correct form is service.namespace, not namespace.service. A query for default.api.svc.cluster.local would be interpreted as a Service named 'default' in the namespace 'api', which does not match the intended resources and would fail DNS resolution.
- ✗
api.svc.default.cluster.local
Why it's wrong here
Here the 'svc' component is incorrectly inserted between the service name and the namespace. The valid structure is always <service>.<namespace>.svc, with 'svc' appearing after the namespace, not before it. Placing 'svc' between api and default breaks the canonical hierarchy, so this name neither matches the service nor conforms to Kubernetes DNS naming rules.
- ✗
api.default.cluster.local
Why it's wrong here
This omits the 'svc' subdomain, which is a mandatory portion of the service DNS FQDN. The sequence '<service>.<namespace>.cluster.local' is not a standard record type; services live under the '<namespace>.svc' subdomain. Without 'svc', the DNS name is incomplete, and CoreDNS will not return the ClusterIP record for the api service.
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Kubernetes Architecture Overview
Key term
Ingress Resources
Ingress Resources are Kubernetes API objects that manage external access to services inside a cluster, typically HTTP and HTTPS traffic, by defining rules for routing requests based on hostnames and paths.
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
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