How would you specifically define a Headless Service in a Kubernetes YAML specification?

How would you specifically define a Headless Service in a Kubernetes YAML specification?

• A. By setting spec.clusterIP:None in the Service YAML specification.
• B. By setting type: Headless in the Service YAML.
• C. By setting spec.clusterIP to 255.255.255.255.
• D. By omitting the clusterIP field entirely.

Answer: (A)

A headless service is defined by disabling the allocation of a cluster IP. In the Service YAML, you specify spec.clusterIP: None. This signals the API server not to allocate a cluster IP for the service, so DNS for the service returns the individual endpoints (pod IPs) instead of a single load-balanced address. This is useful when you want direct access to each pod, such as with StatefulSets or certain service discovery patterns. Why the other ideas don’t fit: there isn’t a type value like Headless for services—the supported types are ClusterIP, NodePort, LoadBalancer, and ExternalName, and a headless behavior is achieved specifically by clusterIP: None. Setting clusterIP to 255.255.255.255 is not valid for a Kubernetes service. Omitting the clusterIP field typically results in a normalClusterIP service being assigned a cluster IP, which would not be headless.

A headless service is defined by disabling the allocation of a cluster IP. In the Service YAML, you specify spec.clusterIP: None. This signals the API server not to allocate a cluster IP for the service, so DNS for the service returns the individual endpoints (pod IPs) instead of a single load-balanced address. This is useful when you want direct access to each pod, such as with StatefulSets or certain service discovery patterns.

Why the other ideas don’t fit: there isn’t a type value like Headless for services—the supported types are ClusterIP, NodePort, LoadBalancer, and ExternalName, and a headless behavior is achieved specifically by clusterIP: None. Setting clusterIP to 255.255.255.255 is not valid for a Kubernetes service. Omitting the clusterIP field typically results in a normalClusterIP service being assigned a cluster IP, which would not be headless.