Reading /etc/group File Format for Supplementary Group Members
This EX200 practice question tests your understanding of manage users and groups. 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.
Refer to the exhibit. A user named 'carol' has been added to the system with the command useradd -G wheel carol. Which line in /etc/group will confirm that carol is now a member of the wheel group?
Why wrong: Incorrect. Although 'carol' appears in this line, the order is different and the list does not match the typical output of `useradd -G`. The `-G` option appends the user to the supplementary group list, so 'carol' should appear at the end, following the existing members 'root,alice,bob'. Additionally, option A places 'carol' first, which is not the default behavior of `useradd -G` on Red Hat systems.
B
wheel:x:10:root,alice,bob,carol
Correct. The `useradd -G wheel carol` command adds 'carol' to the supplementary group 'wheel' by appending her username to the end of the comma-separated member list in `/etc/group`. The line `wheel:x:10:root,alice,bob,carol` shows 'carol' after the existing members, with no trailing comma, which is the correct format.
C
wheel:x:10:root,alice,bob,carol,
Why wrong: Incorrect. This line has a trailing comma after 'carol', which is not valid in `/etc/group`. The member list must not end with a comma.
D
wheel:x:10:root,alice,bob carol
Why wrong: Incorrect. This line uses spaces instead of commas between usernames. The `/etc/group` file requires comma-separated usernames, not spaces.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
wheel:x:10:root,alice,bob,carol
Option B is correct because the `useradd -G wheel carol` command adds 'carol' to the supplementary group 'wheel', and the `/etc/group` file lists supplementary members as a comma-separated list with no trailing comma. The line `wheel:x:10:root,alice,bob,carol` shows 'carol' appended after the existing members, which matches the expected format.
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.
✗
wheel:x:10:carol,root,alice,bob
Why it's wrong here
Incorrect. Although 'carol' appears in this line, the order is different and the list does not match the typical output of `useradd -G`. The `-G` option appends the user to the supplementary group list, so 'carol' should appear at the end, following the existing members 'root,alice,bob'. Additionally, option A places 'carol' first, which is not the default behavior of `useradd -G` on Red Hat systems.
✓
wheel:x:10:root,alice,bob,carol
Why this is correct
Correct. The `useradd -G wheel carol` command adds 'carol' to the supplementary group 'wheel' by appending her username to the end of the comma-separated member list in `/etc/group`. The line `wheel:x:10:root,alice,bob,carol` shows 'carol' after the existing members, with no trailing comma, which is the correct format.
Related concept
Read the scenario before looking for a memorised answer.
✗
wheel:x:10:root,alice,bob,carol,
Why it's wrong here
Incorrect. This line has a trailing comma after 'carol', which is not valid in `/etc/group`. The member list must not end with a comma.
✗
wheel:x:10:root,alice,bob carol
Why it's wrong here
Incorrect. This line uses spaces instead of commas between usernames. The `/etc/group` file requires comma-separated usernames, not spaces.
Common exam traps
Common exam trap: answer the scenario, not the keyword
In Red Hat Enterprise Linux, the /etc/group file format requires member lists to be comma-separated with no trailing comma, and the useradd -G command appends users to the end of the supplementary group member list.
Trap categories for this question
Command / output trap
Incorrect. Although 'carol' appears in this line, the order is different and the list does not match the typical output of `useradd -G`. The `-G` option appends the user to the supplementary group list, so 'carol' should appear at the end, following the existing members 'root,alice,bob'. Additionally, option A places 'carol' first, which is not the default behavior of `useradd -G` on Red Hat systems.
Detailed technical explanation
How to think about this question
The `/etc/group` file uses a colon-delimited format with four fields: group name, password placeholder (usually 'x'), GID, and a comma-separated list of supplementary members. When `useradd -G` is used, the new user is appended to the end of the member list without altering the order of existing users. A trailing comma or space delimiter would cause parsing errors in tools like `getent group` or `groups` command, potentially breaking group membership resolution.
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.
TExam Day Tips
→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 EX200 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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Manage users and groups — This question tests Manage users and groups — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: wheel:x:10:root,alice,bob,carol — Option B is correct because the `useradd -G wheel carol` command adds 'carol' to the supplementary group 'wheel', and the `/etc/group` file lists supplementary members as a comma-separated list with no trailing comma. The line `wheel:x:10:root,alice,bob,carol` shows 'carol' appended after the existing members, which matches the expected format.
What should I do if I get this EX200 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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