Docker Containerization Dockerfile and Image Building 2

Question 1

What defines a multi-stage Docker build?

Accepted Answer

Using multiple FROM instructions in one Dockerfile to copy artifacts between stages and produce a lean final image

Answer

Pushing the same image to multiple registries

Answer

Building separate Dockerfiles in parallel on multiple machines

Answer

Using multiple CMD instructions to run several processes

Question 2

Which 'docker build' flag allows you to stop at a specific named stage in a multi-stage Dockerfile?

Accepted Answer

--target

Answer

--stage

Answer

--from

Answer

--phase

Question 3

How does Docker layer caching improve build performance?

Accepted Answer

Docker reuses cached layers from previous builds when Dockerfile instructions and their context have not changed

Answer

Docker downloads layers in parallel from the registry

Answer

Docker stores only the final image layer and rebuilds intermediates

Answer

Docker caches the build context but always re-executes instructions

Question 4

Which base image is most commonly recommended for minimizing Docker image size in production?

Accepted Answer

alpine:latest

Answer

ubuntu:latest

Answer

centos:7

Answer

debian:latest

Question 5

What happens to Docker's build cache when a Dockerfile instruction changes?

Accepted Answer

The changed layer and all subsequent layers are invalidated and rebuilt

Answer

The entire cache is cleared for all images on the system

Answer

Only the changed layer is rebuilt; subsequent layers are reused

Answer

The cache is unaffected and the old layer is reused

Question 6

What is the best practice for combining shell commands in a RUN instruction to reduce image layers?

Accepted Answer

Chain commands with && in a single RUN instruction

Answer

Use a separate RUN instruction for each command

Answer

Use the SHELL instruction before each command

Answer

Place all commands in a CMD instruction instead

Question 7

In a multi-stage Dockerfile, how do you copy a file from a previous build stage into the current stage?

Accepted Answer

COPY --from=

Answer

ADD --stage=

Answer

RUN copy --stage

Answer

IMPORT --from=