CKA Workloads and Scheduling Practice Question
A DaemonSet is expected to run on all nodes, but a particular node does not have the pod. The node is Ready and has no taints. You run 'kubectl describe daemonset <name>' and see 'MISSING' for that node. What is a likely cause?
⚠ Common exam trap
Watch out — candidates often assume 'MISSING' implies a resource or taint issue, but the CKA exam tests the understanding that nodeSelector mismatches cause the DaemonSet controller to skip the node entirely, not just fail to schedule.
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
✓
The DaemonSet has a nodeSelector that the node does not match
When a DaemonSet shows 'MISSING' for a specific node that is Ready and has no taints, the most common cause is that the node does not match the DaemonSet's nodeSelector. The nodeSelector field in the DaemonSet spec defines a set of key-value pairs that must match the node's labels. If the node lacks the required labels, the DaemonSet controller will not schedule the pod on that node, resulting in the 'MISSING' status.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The DaemonSet is configured to run only on control plane nodes
Why it's wrong here
If the DaemonSet were configured to target only control plane nodes, it would be absent from all worker nodes in the cluster. Because the scenario specifies that the DaemonSet is missing from only one specific node while running on others, a global restriction to control plane nodes cannot be the cause.
- ✓
The DaemonSet has a nodeSelector that the node does not match
Why this is correct
The DaemonSet controller uses the nodeSelector field to match node labels before scheduling pods. If a specific node lacks the required label or has a mismatched value, the controller will intentionally skip scheduling the DaemonSet pod on that node, leaving it as the sole exception.
- ✗
The node has insufficient resources for the DaemonSet pod
Why it's wrong here
When a node lacks CPU or memory to run a DaemonSet pod, the Kubernetes scheduler still creates the Pod object, but it remains stuck in a Pending state with a resource-related event. The pod would not be completely absent or missing from the node's scheduled workload list; it would simply fail to run.
- ✗
The node has a taint that is not tolerated
Why it's wrong here
While an untolerated taint would prevent a DaemonSet pod from scheduling, standard worker nodes do not have custom taints applied by default. Additionally, DaemonSets automatically tolerate common system taints like node.kubernetes.io/unschedulable, meaning a typical node status issue would not prevent scheduling unless a unique, custom taint was manually configured.
Go deeper
Related to this question
Learn chapter
Troubleshooting Cluster and Node Issues
Key term
DaemonSets
A DaemonSet is a Kubernetes object that ensures a copy of a specific pod runs on every node in a cluster, or on a subset of nodes.
Key term
Node Affinity
Node Affinity is a set of rules used by Kubernetes to determine which nodes a pod can be scheduled on, based on labels assigned to the nodes.
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JA
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.