CKAD Application Design and Build Practice Question
Which THREE of the following are valid fields in the '.spec' of a Job manifest?
⚠ Common exam trap
Candidates often confuse Job fields with Deployment fields, assuming 'replicas' or 'strategy' apply to Jobs, when in fact Jobs use 'completions' and 'parallelism' to manage batch execution.
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
✓
parallelism
'parallelism' is a valid field in the '.spec' of a Job manifest. It controls the maximum number of Pods that can run concurrently for the Job, allowing you to manage parallel execution. This field is part of the Job specification in the Kubernetes API, distinct from Deployments or other controllers.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
replicas
Why it's wrong here
The replicas field is not valid in a Job's spec because Jobs do not maintain a desired steady-state number of Pods; they run a fixed task to completion. Replicas belongs to continuous controllers like Deployments, ReplicaSets, or StatefulSets, which constantly reconcile Pod counts. In a Job, the parallelism field controls concurrency, and the controller decides Pod creation based on completions and failures, not on a static replica count.
- ✓
parallelism
Why this is correct
parallelism specifies the maximum number of Job Pods that can run simultaneously. It does not define the total number of Pods; it only sets the concurrency cap for the Job. For a non-parallel Job, parallelism is implicitly 1, but for a parallel Job, you can set it higher to process multiple work items at once. This field is useful for controlling resource usage and throttling the rate at which work is processed.
- ✗
strategy
Why it's wrong here
The strategy field is part of a Deployment's spec, where it controls the rollout approach, such as RollingUpdate or Recreate. A Job has no rolling update mechanism because it is a one-time execution; the Job controller creates Pods from the template and tracks success/failure without needing a strategy. Including strategy in a Job spec would be ignored or rejected, as it has no meaning in this context.
- ✓
completions
Why this is correct
completions defines the number of successfully finished Pods required for the Job to be considered complete. For a non-parallel Job, this is usually unset or 1, meaning a single successful Pod finishes the Job. For a parallel Job, you can set completions to the total number of work items; when that many Pods have exited with code 0, the Job ends. This field is essential for running batch jobs that need to process a known number of tasks.
- ✓
backoffLimit
Why this is correct
backoffLimit sets the maximum number of times the Job will retry a failed Pod before being marked as Failed. The default is 6, but you can adjust it based on your application's tolerance for transient errors. Each failed Pod counts as one attempt, and if the limit is exceeded, the Job controller terminates the Job and generates an event. Note that with restartPolicy: OnFailure, container restarts inside the same Pod do not increment this limit; only Pod terminations do.
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