200-901 Application Deployment and Security Practice Question
In a Dockerfile, which instruction is used to set an environment variable that will be available at runtime?
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
✓
ENV
ENV sets environment variables in the image that persist when the container runs.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
RUN export VAR=value
Why it's wrong here
This sets a variable only during the build step, not persisted.
- ✓
ENV
Why this is correct
ENV sets environment variables for the container runtime.
- ✗
LABEL
Why it's wrong here
LABEL adds metadata, not runtime environment variables.
- ✗
ARG
Why it's wrong here
ARG defines build-time variables that are not available at runtime.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-901 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-901 exam.