Which term describes the registry-provided, content-addressable identifier for a specific image?

Which term describes the registry-provided, content-addressable identifier for a specific image?

• A. Tag
• B. Image ID
• C. Label
• D. Digest

Answer: (D)

The concept being tested is how a container image is uniquely identified by content from the registry. The registry-provided, content-addressable identifier for a specific image is called a digest. This digest is derived from the image’s content (the manifest and layers) and remains immutable, so it always points to exactly that exact image version. It’s typically shown as a sha256:… value and is used to pin a precise image in deployments, ensuring you pull the exact content you expect. In contrast, a tag is just a human-friendly alias like "latest" that can move to different image contents over time, which is why it’s not suitable for guaranteeing the exact image. An Image ID is a local identifier used by a container runtime on a specific host, not the registry’s identifier for the image. A Label is metadata attached to an image, not the identifier itself.

The concept being tested is how a container image is uniquely identified by content from the registry. The registry-provided, content-addressable identifier for a specific image is called a digest. This digest is derived from the image’s content (the manifest and layers) and remains immutable, so it always points to exactly that exact image version. It’s typically shown as a sha256:… value and is used to pin a precise image in deployments, ensuring you pull the exact content you expect.

In contrast, a tag is just a human-friendly alias like "latest" that can move to different image contents over time, which is why it’s not suitable for guaranteeing the exact image. An Image ID is a local identifier used by a container runtime on a specific host, not the registry’s identifier for the image. A Label is metadata attached to an image, not the identifier itself.