- A
ENTRYPOINT python app.py
Why wrong: ENTRYPOINT is also possible but typically used for the main command; CMD is more appropriate for specifying arguments or a simple default command.
- B
RUN python app.py
Why wrong: RUN executes commands during image build, not at container start.
- C
CMD python app.py
Correct. CMD provides default command for container execution.
- D
STARTUP python app.py
Why wrong: STARTUP is not a valid Dockerfile instruction.
Question 626 of 1,000
XK0-005 Scripting, Containers, and Automation Practice Question
This XK0-005 practice question tests your understanding of scripting, containers, and automation. 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 system administrator needs to create a Dockerfile for a Python application. The application should be installed in the container, and when the container starts, it should run the command 'python app.py'. Which Dockerfile instruction should be used to specify the default command?
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
✓
CMD python app.py
CMD specifies the default command to run when the container starts. ENTRYPOINT can also be used but is typically for executables that are not easily overridden.
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.
- ✗
ENTRYPOINT python app.py
Why it's wrong here
ENTRYPOINT is also possible but typically used for the main command; CMD is more appropriate for specifying arguments or a simple default command.
- ✗
RUN python app.py
Why it's wrong here
RUN executes commands during image build, not at container start.
- ✓
CMD python app.py
Why this is correct
Correct. CMD provides default command for container execution.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
STARTUP python app.py
Why it's wrong here
STARTUP is not a valid Dockerfile instruction.
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
ENTRYPOINT is also possible but typically used for the main command; CMD is more appropriate for specifying arguments or a simple default command.
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 XK0-005 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 XK0-005 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.
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FAQ
Questions learners often ask
What does this XK0-005 question test?
Scripting, Containers, and Automation — This question tests Scripting, Containers, and Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: CMD python app.py — CMD specifies the default command to run when the container starts. ENTRYPOINT can also be used but is typically for executables that are not easily overridden.
What should I do if I get this XK0-005 question wrong?
Identify which XK0-005 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
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Last reviewed: Jul 4, 2026
This XK0-005 practice question is part of Courseiva's free CompTIA 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 XK0-005 exam.
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