easyMultiple ChoiceObjective-mapped

200-901 Practice Question: Refer to the exhibit

Exhibit

FROM python:3.9-slim
WORKDIR /app
COPY requirements.txt .
RUN pip install -r requirements.txt
COPY . .
EXPOSE 5000
CMD ["python", "app.py"]

Refer to the exhibit. The Docker image built from this Dockerfile is larger than expected. Which optimization should be recommended?

⚠ Common exam trap

Cisco often tests the misconception that reducing the number of layers (Option B) or using a smaller base image (Option A) is the primary way to shrink image size, when in fact multi-stage builds are the correct, targeted solution for removing build-time artifacts that inflate the final image.

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

✓

Use a multi-stage build.

Multi-stage builds allow you to use multiple FROM statements in your Dockerfile. You can compile or install dependencies in an intermediate stage using a full-featured base image, then copy only the necessary artifacts (e.g., compiled code, libraries) into a final, minimal runtime image. This dramatically reduces the final image size by discarding build tools, temporary files, and unnecessary layers from the earlier stages.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Use a smaller base image like python:3.9-alpine.
Why it's wrong here
This is a valid optimization but not the most recommended for this simple case; multi-stage build is more comprehensive.
✗
Combine RUN and COPY layers to reduce layers.
Why it's wrong here
This reduces layers but not the actual size; cache inefficiency may increase build time.
✗
Remove the EXPOSE instruction.
Why it's wrong here
EXPOSE is metadata and does not affect image size.
✓
Use a multi-stage build.
Why this is correct
Multi-stage builds allow copying only necessary artifacts, significantly reducing the final image size.

Go deeper

200-901 Practice Question: Refer to the exhibit

Exhibit

Why each option matters

Option-by-option breakdown

Related to this question