A Dockerfile installs system packages and Python dependencies. The developer notices that the image is larger than expected and wants to reduce the number of layers. Which change to the Dockerfile would help?

Combine multiple `RUN` commands into a single `RUN` command using `&&`

Use `VOLUME` to store installed packages

Use `ADD` instead of `COPY` for copying requirements files

Use `CMD` instead of `RUN` for installation

A Dockerfile currently has the following instructions in order: FROM ubuntu:20.04, RUN apt-get update && apt-get install -y curl, COPY . /app, RUN curl -o /app/data.tar.gz https://example.com/data.tar.gz. The developer wants to improve cache efficiency so that the apt-get layer is not re-run when the source code changes. Which change is most effective?

Combine the RUN apt-get and RUN curl into a single RUN

Place the COPY . /app before the RUN apt-get

Move the COPY . /app instruction to after the RUN curl instruction

Use ADD instead of COPY for the source code

In a Dockerfile, what is the purpose of the `ENV` instruction?

To declare a volume for persistent storage

To specify the working directory for the container

To define environment variables that are available in the container

A Python application reads a database connection string from the environment variable DB_URL. The Dockerfile must set a default value so the container runs without additional configuration, but operators need to override it at runtime. Which instruction should be used?

ENV DB_URL=postgres://default:5432/mydb

ARG DB_URL=postgres://default:5432/mydb

RUN export DB_URL=postgres://default:5432/mydb

CiscoCertified Network Associate Automation (CCNA Automation)

Domain 4Objective 6

6. Interpret Contents of a Dockerfile 200-901 Practice Questions (Page 1)

Part of the 4.0 Application Deployment and Security domain, which accounts for 15% of the 200-901 exam. Cisco does not publish an official question count, but from its 120-minute exam (~50–80 total, ~8–12 in this domain), expect 1–1 from this objective — we provide 43 practice questions to prepare you well beyond it. (estimate)

43questions here

9free pages

12concepts

15%of the exam

Questions 1–5

1application · medium
A Dockerfile installs system packages and Python dependencies. The developer notices that the image is larger than expected and wants to reduce the number of layers. Which change to the Dockerfile would help?
Select an answer first
2application · medium
A Dockerfile currently has the following instructions in order: FROM ubuntu:20.04, RUN apt-get update && apt-get install -y curl, COPY . /app, RUN curl -o /app/data.tar.gz https://example.com/data.tar.gz. The developer wants to improve cache efficiency so that the apt-get layer is not re-run when the source code changes. Which change is most effective?
Select an answer first
3foundation · easy
In a Dockerfile, what is the purpose of the `ENV` instruction?
Select an answer first
4application · easy
A Python application reads a database connection string from the environment variable DB_URL. The Dockerfile must set a default value so the container runs without additional configuration, but operators need to override it at runtime. Which instruction should be used?
Select an answer first
5application · medium
A containerized database application stores data in `/var/lib/db`. The data must persist across container restarts and removals. The Dockerfile should declare a mount point for this directory. Which instruction should be added?
Select an answer first

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6. Interpret Contents of a Dockerfile 200-901 Practice Questions (Page 1)

Questions 1–5

A Dockerfile installs system packages and Python dependencies. The developer notices that the image is larger than expected and wants to reduce the number of layers. Which change to the Dockerfile would help?

In a Dockerfile, what is the purpose of the `ENV` instruction?

A Python application reads a database connection string from the environment variable DB_URL. The Dockerfile must set a default value so the container runs without additional configuration, but operators need to override it at runtime. Which instruction should be used?

A containerized database application stores data in `/var/lib/db`. The data must persist across container restarts and removals. The Dockerfile should declare a mount point for this directory. Which instruction should be added?

Keep studying — 4.0 Application Deployment and Security