Question 1hardmultiple choice
Full question →- A
SHA-512
$6$ corresponds to SHA-512.
- B
SHA-256
Why wrong: SHA-256 is indicated by $5$.
- C
MD5
Why wrong: MD5 is indicated by $1$.
- D
Blowfish
Why wrong: Blowfish is indicated by $2a$ or $2b$.
Question 483 of 522
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.
In the /etc/shadow file, a user's password hash begins with '$6$'. What hash algorithm does this prefix indicate?
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
✓
SHA-512
The prefix '$6$' in the /etc/shadow file indicates that the password hash was generated using the SHA-512 (Secure Hash Algorithm 512-bit) algorithm. This is defined in the crypt(3) function's modular crypt format, where $1$ is MD5, $5$ is SHA-256, and $6$ is SHA-512. SHA-512 is the strongest of the commonly used hash algorithms in Linux password hashing, providing a 512-bit digest.
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.
- ✓
SHA-512
Why this is correct
$6$ corresponds to SHA-512.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
SHA-256
Why it's wrong here
SHA-256 is indicated by $5$.
- ✗
MD5
Why it's wrong here
MD5 is indicated by $1$.
- ✗
Blowfish
Why it's wrong here
Blowfish is indicated by $2a$ or $2b$.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the prefix '$6$' with SHA-256 (which uses '$5$') or mistakenly associate '$6$' with Blowfish due to similar numbering, but the correct mapping is $1$=MD5, $5$=SHA-256, $6$=SHA-512.
Detailed technical explanation
How to think about this question
The modular crypt format (MCF) used in /etc/shadow allows the system to identify the hash algorithm from the prefix, enabling support for multiple algorithms simultaneously. SHA-512 (prefix $6$) uses 5000 rounds by default (configurable via the rounds= parameter) and produces a 86-character hash string, making it resistant to brute-force attacks. In real-world scenarios, administrators may increase the round count to slow down password cracking attempts, but this also increases authentication latency.
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 — study guide chapter
Learn the concepts, then practise the questions
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Administrative Tasks practice questions
Targeted practice on this topic area only
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FAQ
Questions learners often ask
What does this LPIC-1 question test?
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: SHA-512 — The prefix '$6$' in the /etc/shadow file indicates that the password hash was generated using the SHA-512 (Secure Hash Algorithm 512-bit) algorithm. This is defined in the crypt(3) function's modular crypt format, where $1$ is MD5, $5$ is SHA-256, and $6$ is SHA-512. SHA-512 is the strongest of the commonly used hash algorithms in Linux password hashing, providing a 512-bit digest.
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.
About these practice questions
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Last reviewed: Jun 25, 2026
This LPIC-1 practice question is part of Courseiva's free LPI 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 LPIC-1 exam.
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