Certified Kubernetes Application Developer (CKAD) Practice Test

In a Kubernetes context, what is a primary use of a headless service?

1. To load balance traffic among pods

2. To provide direct access to pods

3. To manage persistent storage

4. To expose the service externally

The correct answer is: To provide direct access to pods

A headless service in Kubernetes is primarily used to provide direct access to the individual pods that are a part of the service without the intermediate load balancer. When a headless service is created, it does not allocate a ClusterIP, which means that it does not function like a regular service that would distribute traffic evenly across the pods. Instead, it enables DNS resolution of the individual pod IPs, allowing clients to connect directly to any specific pod. This direct access can be beneficial in scenarios such as stateful applications where the identity and network address of each pod are important. For instance, headless services are often used in StatefulSets to allow applications to communicate directly with each instance of the pod, making it easier for applications that rely on persistent data or need to handle session affinity. The other options do not accurately describe the primary use of a headless service. Load balancing traffic among pods is the functionality provided by regular services that have a ClusterIP. Managing persistent storage typically involves Persistent Volumes and Persistent Volume Claims. Exposing a service externally usually involves using NodePort or LoadBalancer types of services, which are designed to route traffic from outside the cluster to services running internally.