CKAD Services and Networking Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  kubectl expose deployment web-app --port=8080 --target-port=8080 --selector=app=web

  Why this is correct

  This command correctly creates a Service from the existing Deployment named web-app. The --selector=app=web flag ensures the Service's label selector matches the pods that belong to the Deployment, so traffic is routed only to those pod replicas. Port 8080 is set as the Service port (the port clients connect to) and --target-port=8080 forwards traffic to the same port on the selected pods, which is appropriate if the container listens on 8080. Because kubectl expose defaults to ClusterIP, this yields an internal stable IP for intra-cluster communication.

• ✗

  kubectl expose deployment web-app --port=8080 --target-port=8080 --type=ClusterIP

  Why it's wrong here

  This command omits the --selector flag, so kubectl expose will automatically copy the Deployment's own label selector into the Service. If the Deployment's selector is not app=web, the Service will target the wrong pods or none at all, failing to reach the intended backend. Additionally, specifying --type=ClusterIP is redundant because that is already the default Service type, so it adds no value here. The explicit --selector=app=web is required to guarantee the Service correctly maps to the Deployment's pods.

• ✗

  kubectl run web-app --image=nginx --port=8080 --expose

  Why it's wrong here

  This command does not expose the existing Deployment; instead, it creates a brand-new Deployment (or Pod, depending on kubectl version) named web-app with the nginx image and then creates a Service to expose that new workload. The target-port 8080 is set on the new container, but this has no connection to the existing Deployment's pods or their labels. Since the goal is to create a Service for the already-running Deployment, this command would create duplicate resources and likely cause confusion or conflicts rather than exposing the intended workload.

• ✗

  kubectl create service clusterip web-app --tcp=8080:8080 --selector=app=web

  Why it's wrong here

  The kubectl create service clusterip command cannot accept a --selector flag; this flag is simply not supported by that subcommand, so the command will fail with an error. Even if it did accept the flag, this approach creates a Service in isolation without linking it to the Deployment object, meaning the Service's selector must be manually maintained and there is no automatic synchronization of endpoints. The kubectl expose command is the proper way to generate a Service from an existing resource because it derives the selector and port configuration from the Deployment's spec.

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