CKAD Application Design and Build Practice Question
Which TWO of the following are valid fields in a CronJob spec? (Select 2)
⚠ Common exam trap
CNCF often tests the distinction between CronJob spec fields and Job spec fields, trapping candidates who confuse `completions` and `parallelism` (Job-level) with CronJob-level fields like `schedule` and `concurrencyPolicy`.
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
✓
concurrencyPolicy
B is correct because `concurrencyPolicy` is a valid field in a CronJob spec that controls how concurrent executions of the job are handled. It can be set to `Allow`, `Forbid`, or `Replace`, which determines whether a new job can start while a previous one is still running.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
restartPolicy
Why it's wrong here
restartPolicy is a valid field in the Pod template inside the jobTemplate, not in CronJob.spec. In fact, the Job pod template requires restartPolicy to be either Never or OnFailure, but a CronJob itself does not define container restart behavior. Placing restartPolicy at the CronJob level would be rejected by the API server as an unknown field.
- ✓
concurrencyPolicy
Why this is correct
concurrencyPolicy is a legitimate CronJob.spec field that controls how the controller handles Jobs that should be created while another Job from the same CronJob is still active. It accepts Allow, Forbid, or Replace; Allow starts a new Job immediately, Forbid skips the new run until the next schedule, and Replace cancels the active Job before starting a new one. This is a top-level scheduling-policy field, not something inherited from the Pod or Job template.
- ✗
completions
Why it's wrong here
completions is a field of the Job specification, specifically .spec.jobTemplate.spec.completions, defining how many successful pods must finish before the Job is complete. A CronJob only embeds a Job template under its own .spec.jobTemplate; it never accepts completions directly at the CronJob.spec level. Trying to set completions as a direct CronJob field would be invalid because the CronJob spec has a fixed schema that does not include it.
- ✓
schedule
Why this is correct
schedule is a required top-level field in CronJob.spec that takes a cron expression (such as '*/5 * * * *' or '@hourly'), telling the CronJob controller exactly when to create the Job object. This field directly corresponds to the 'cron' in CronJob and is analogous to the schedule line in a crontab file. The controller compares the schedule to the current time to decide whether to launch a Job.
- ✗
parallelism
Why it's wrong here
parallelism is a Job-level field, found at .spec.jobTemplate.spec.parallelism, that sets the maximum number of Pods that may run concurrently for that single Job. A CronJob schedules new Job objects, so any pod-level concurrency belongs inside the Job template, not the CronJob spec. Using parallelism directly in the CronJob spec is invalid and will be rejected by kubectl validation.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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