- A
RUN
Why wrong: RUN executes commands, not for variable definition.
- B
ARG
ARG defines build-time variables that can be overridden.
- C
ENV
Why wrong: ENV sets environment variables available at runtime, not build-time adjustable.
- D
CMD
Why wrong: CMD sets default command, not variables.
Question 672 of 1,000
200-901 Application Deployment and Security Practice Question
This 200-901 practice question tests your understanding of application deployment and security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A developer is writing a Dockerfile for a Node.js application. They want to set a build-time variable for the application version that can be changed without modifying the Dockerfile. Which instruction should be used?
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
✓
ARG
ARG allows passing build-time variables. ENV sets environment variables that persist in the container. CMD and RUN are not for variable definition.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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
Why it's wrong here
RUN executes commands, not for variable definition.
- ✓
ARG
Why this is correct
ARG defines build-time variables that can be overridden.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
ENV
Why it's wrong here
ENV sets environment variables available at runtime, not build-time adjustable.
- ✗
CMD
Why it's wrong here
CMD sets default command, not variables.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Trap categories for this question
Command / output trap
RUN executes commands, not for variable definition.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 200-901 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which 200-901 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
- →
Application Deployment and Security — study guide chapter
Learn the concepts, then practise the questions
- →
Application Deployment and Security practice questions
Targeted practice on this topic area only
- →
All 200-901 questions
1,000 questions across all exam domains
- →
Cisco DevNet Associate 200-901 study guide
Full concept coverage aligned to exam objectives
- →
200-901 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related 200-901 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Software Development and Design practice questions
Practise 200-901 questions linked to Software Development and Design.
Understanding and Using APIs practice questions
Practise 200-901 questions linked to Understanding and Using APIs.
Application Deployment and Security practice questions
Practise 200-901 questions linked to Application Deployment and Security.
Cisco Platforms and Development practice questions
Practise 200-901 questions linked to Cisco Platforms and Development.
Network Fundamentals practice questions
Practise 200-901 questions linked to Network Fundamentals.
Infrastructure and Automation practice questions
Practise 200-901 questions linked to Infrastructure and Automation.
200-901 fundamentals practice questions
Practise 200-901 questions linked to 200-901 fundamentals.
200-901 scenario practice questions
Practise 200-901 questions linked to 200-901 scenario.
200-901 troubleshooting practice questions
Practise 200-901 questions linked to 200-901 troubleshooting.
Practice this exam
Start a free 200-901 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this 200-901 question test?
Application Deployment and Security — This question tests Application Deployment and Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: ARG — ARG allows passing build-time variables. ENV sets environment variables that persist in the container. CMD and RUN are not for variable definition.
What should I do if I get this 200-901 question wrong?
Identify which 200-901 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jul 4, 2026
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.