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DCA · Question #161

You set up an automatic pruning policy on a DTR repository to prune all images using Apache licenses. What effect does this have on images in this repository?

The correct answer is A. Matching images are untagged once they are older than the pruning threshold set in the. DTR pruning policies untag images that match specified criteria and are older than a defined threshold, making them less discoverable but not immediately deleting the underlying layers.

Submitted by tom_us· Apr 18, 2026Image Creation, Management, and Registry

Question

You set up an automatic pruning policy on a DTR repository to prune all images using Apache licenses. What effect does this have on images in this repository?

Options

  • AMatching images are untagged once they are older than the pruning threshold set in the
  • BMatching Images are untagged during the next prune job.
  • CMatching images are deleted during the next prune Job.
  • DMatching images are untagged during the next prune job, and subsequently deleted once they are

How the community answered

(21 responses)
  • A
    95% (20)
  • B
    5% (1)

Why each option

DTR pruning policies untag images that match specified criteria and are older than a defined threshold, making them less discoverable but not immediately deleting the underlying layers.

AMatching images are untagged once they are older than the pruning threshold set in theCorrect

Docker Trusted Registry (DTR) pruning policies are designed to untag images that meet the policy's criteria (e.g., specific license, tag pattern) *and* have exceeded a configured age threshold. This untagging action removes the tag from the image, making it less discoverable but not immediately deleting the underlying image layers; deletion only occurs during garbage collection if no other tags or manifests refer to them.

BMatching Images are untagged during the next prune job.

While untagging occurs during a prune job, this choice is incorrect because it misses the crucial condition of the image's age relative to the pruning threshold.

CMatching images are deleted during the next prune Job.

DTR pruning policies untag images; they do not directly delete images, as deletion of layers only happens later during garbage collection.

DMatching images are untagged during the next prune job, and subsequently deleted once they are

This choice incorrectly implies immediate subsequent deletion due to the prune job itself and also misses the age threshold condition for untagging.

Concept tested: DTR image pruning policy behavior

Source: https://docs.mirantis.com/docker-enterprise/v3.2/dtr/configure/manage-image-pruning.html

Topics

#DTR#Pruning policies#Image lifecycle#Registry management

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