The answer is that the /etc/shadow file’s purpose is to securely store encrypted passwords and password aging information. This is correct because the second field of each line in /etc/shadow contains the encrypted password hash, while subsequent fields track the last password change date, minimum and maximum password age, warning period, and inactivity period, allowing the system to enforce password expiration policies. On the LPIC-1 exam, this concept tests your understanding of Linux authentication security, often appearing in questions about file permissions and user account management. A common trap is confusing /etc/shadow with /etc/passwd, which stores user IDs and shell paths but never encrypted passwords. Remember the mnemonic: “Shadow hides the hash” — the shadow file is only readable by root, keeping password hashes out of the world-readable /etc/passwd.
LPIC-1 Administrative Tasks Practice Question
This LPIC-1 practice question tests your understanding of administrative tasks. 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.
Which THREE of the following statements are true about the /etc/shadow file?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It can contain password expiration information
The /etc/shadow file stores password expiration information, such as the last password change date, minimum and maximum password age, warning period, and inactivity period. This data is used by the system to enforce password aging policies, making option B correct.
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.
✗
It contains the encrypted passwords in the second field, replacing the 'x' in /etc/passwd
Why it's wrong here
The 'x' in /etc/passwd indicates password is in shadow; shadow file does not replace it.
✓
It can contain password expiration information
Why this is correct
Fields like last change, min/max days, warning period are in shadow.
Related concept
Read the scenario before looking for a memorised answer.
✓
It is readable only by the root user
Why this is correct
Permissions are typically 000 or 600, readable only by root.
Related concept
Read the scenario before looking for a memorised answer.
✓
The second field contains the encrypted password
Why this is correct
The second field is the encrypted password hash.
Related concept
Read the scenario before looking for a memorised answer.
✗
It is world-readable to allow any user to verify passwords
Why it's wrong here
It is not world-readable; only root can read it.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the purpose of /etc/shadow with /etc/passwd, mistakenly thinking the second field of /etc/shadow contains a placeholder like 'x' instead of the actual encrypted password hash.
Detailed technical explanation
How to think about this question
The /etc/shadow file uses a colon-delimited format with nine fields: username, encrypted password (using algorithms like SHA-512, indicated by $6$), last password change date (in days since epoch), minimum age, maximum age, warning period, inactivity period, expiration date, and a reserved field. Password aging is enforced by the pam_unix module, which reads these fields during authentication to determine if a password change is required.
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 LPIC-1 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.
Administrative Tasks — This question tests Administrative Tasks — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: It can contain password expiration information — The /etc/shadow file stores password expiration information, such as the last password change date, minimum and maximum password age, warning period, and inactivity period. This data is used by the system to enforce password aging policies, making option B correct.
What should I do if I get this LPIC-1 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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