CKA Workloads and Scheduling Practice Question
A node has a taint 'gpu=true:NoSchedule'. A pod has a toleration 'key: gpu, operator: Exists, effect: NoSchedule'. Will the pod be scheduled on the node?
⚠ Common exam trap
It's easy for candidates to assume a toleration must specify a `value` to match a taint, forgetting that the `Exists` operator with no `value` field matches any value for the given key, making the toleration valid even without an explicit value match.
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
✓
Yes, because the toleration matches the taint
A toleration with `operator: Exists` and no `value` field matches any taint that has the specified key (`gpu`) and effect (`NoSchedule`), regardless of the taint's value. The taint `gpu=true:NoSchedule` has the key `gpu` and effect `NoSchedule`, so the toleration matches it perfectly, allowing the pod to be scheduled on the node. Tolerations do not require a value when using the `Exists` operator, as it checks only for the key and effect.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Yes, because the toleration matches the taint
Why this is correct
When a pod's toleration matches the key, value, and effect of a node's taint, the Kubernetes scheduler is permitted to schedule the pod onto that node. Tolerations do not force scheduling, but they successfully bypass the NoSchedule restriction imposed by the matching taint.
- ✗
Yes, only if the pod has a nodeSelector for gpu
Why it's wrong here
While a nodeSelector or node affinity can be used to steer a pod to a specific node, it is not a prerequisite for overcoming a taint. A matching toleration alone is sufficient to allow scheduling on a tainted node, as taints only repel pods rather than attract them.
- ✗
No, because the toleration does not specify a value
Why it's wrong here
If a toleration uses the Exists operator, it does not need to specify a value to match the taint. The Exists operator matches any value associated with the specified key, making the toleration fully valid and capable of allowing scheduling.
- ✗
No, because the node also has other taints
Why it's wrong here
There is no indication in the scenario that the node has any additional taints beyond gpu=true:NoSchedule. Even if other taints existed, they would only block the pod if the pod lacked corresponding tolerations for those specific taints, which is outside the scope of this question.
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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.