CKA Services and Networking Practice Question
You have a headless service named 'my-headless' with clusterIP: None. A pod in the same namespace queries the DNS name 'my-headless'. What will the DNS response contain?
⚠ Common exam trap
Watch out — candidates often confuse headless services with normal ClusterIP services, assuming DNS will return a single virtual IP or an error, rather than understanding that headless services return multiple pod IPs for direct pod-to-pod resolution.
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
✓
A list of A records for each pod matching the service selector.
A headless service (clusterIP: None) does not have a ClusterIP or load-balance traffic. Instead, DNS queries for the service name return A records for the individual pod IPs that match the service's selector. This allows direct pod-to-pod communication without a proxy, as defined by Kubernetes DNS specification.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
An error because headless services cannot be queried by DNS.
Why it's wrong here
It is not an error. Kubernetes' internal DNS (CoreDNS by default) resolves all Service names, including headless Services. For a headless Service with a selector, a DNS query returns the set of pod IPs as multiple A records rather than failing; therefore the query is valid and produces useful endpoint discovery data.
- ✗
A single A record with the service's IP.
Why it's wrong here
This confuses ClusterIP Services with headless Services. A standard Service gets a virtual ClusterIP and DNS returns a single A record pointing to that IP, but a headless Service sets clusterIP: None, so no Service-level IP exists to return. Instead, DNS supplies the individual pod IPs that match the selector as separate A records.
- ✗
The ClusterIP of the service (which is None).
Why it's wrong here
clusterIP: None is a configuration marker, not a routable address: it instructs CoreDNS to bypass the Service proxy and publish endpoint IPs directly. The value None is never carried in or returned by DNS. A DNS lookup for this headless Service will contain the A records of the selected pods, never a record with the literal string None or a ClusterIP address.
- ✓
A list of A records for each pod matching the service selector.
Why this is correct
A headless Service with a selector creates Endpoints (or EndpointSlices) from the ready pods that match the labels. When a client looks up this Service name, CoreDNS returns one A record for each such pod IP, allowing direct pod discovery. This behavior is fundamental to StatefulSets, where each pod gets its own DNS name from this list.
Visual reference
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Related to this question
Learn chapter
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
ClusterIP NodePort LoadBalancer
ClusterIP, NodePort, and LoadBalancer are three types of Kubernetes Services that control how traffic reaches your application pods inside the cluster or from outside.
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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.