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Docker

Image Layers, Digests, and Tags

Distinguish image layers, mutable tags, immutable digests, and local image records so deployments can identify exact content.

Intermediate14 min read
Docker lessonContainer and orchestration foundationsPractice

UNTIMED COACHING

Practice before the pressure

Use feedback to correct the model, not merely memorize an option position.

GUIDED PRACTICE

Practice the lesson questions

Answer normal lesson questions without a timer. Every answer includes an explanation, and incorrect answers can be tried again before continuing.

CONCEPT MODELS

See the lesson as a system

Use these visual guides to connect the key ideas before answering the questions.

Connect the roles in Image Layers, Digests, and TagsKeep image layer, layer content, tag pointer, and digest identity as separate workload roles.
Connect the roles in Image Layers, Digests, and TagsA topic-specific model connects four distinct roles used to reason about image layers, digests, and tags.
Image packagePackage is assembled from read-only layers
Layer dataData can be shared across images
Tag mappingMapping can move to different content
Content identityIdentity pins exact image bytes
Verify Local image recordConnect local image record with its topic-specific inspection, expected outcome, and protected workload boundary.
Verify Local image recordA verification model for image layers, digests, and tags connects the final workload decision to its check, result, and protected boundary.
Verification checkCheck compares local and approved identity
Starting checkInspect verification check
Expected resultConfirm verification check
Safety boundaryProtect image package scope