Quick Answer
The answer is the output of the 'last' command, which is the best artefact for determining recent SSH login attempts when auth.log has been deleted. This is because the 'last' command reads the binary file /var/log/wtmp, which persistently records all successful logins and logouts, including SSH sessions, and is not dependent on the text-based auth.log. On the Computer Hacking Forensic Investigator CHFI exam, this tests your understanding of Linux log file hierarchy and the distinction between volatile text logs (auth.log) and persistent binary logs (wtmp). A common trap is assuming auth.log is the only source for login data, but attackers often delete it to hide their tracks, making wtmp a critical forensic artefact. Remember the mnemonic: "When auth is gone, last logs on."
This CHFI practice question tests your understanding of os and network forensics. 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.
During a Linux forensic investigation, you find that the file /var/log/auth.log has been deleted. Which of the following artefacts would BEST help determine recent SSH login attempts?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Contents of /etc/shadow
Why wrong: /etc/shadow stores password hashes, not login history.
Bash history from /root/.bash_history
Why wrong: Bash history shows commands, not login attempts.
Cron job entries in /etc/crontab
Why wrong: Cron entries show scheduled tasks, not logins.
Output of the 'last' command
'last' shows login records from /var/log/wtmp, useful for recent SSH attempts.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Output of the 'last' command
The 'last' command reads /var/log/wtmp, which records all logins and logouts, including SSH sessions.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Contents of /etc/shadow
Why it's wrong here
/etc/shadow stores password hashes, not login history.
Bash history from /root/.bash_history
Why it's wrong here
Bash history shows commands, not login attempts.
Cron job entries in /etc/crontab
Why it's wrong here
Cron entries show scheduled tasks, not logins.
Output of the 'last' command
Why this is correct
'last' shows login records from /var/log/wtmp, useful for recent SSH attempts.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
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
Bash history shows commands, not login attempts.
Detailed technical explanation
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the CHFI 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
Identify which CHFI 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.
OS and Network Forensics — study guide chapter
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FAQ
OS and Network Forensics — This question tests OS and Network Forensics — Read the scenario before looking for a memorised answer..
The correct answer is: Output of the 'last' command — The 'last' command reads /var/log/wtmp, which records all logins and logouts, including SSH sessions.
Identify which CHFI 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.
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 21, 2026
This CHFI practice question is part of Courseiva's free EC-Council 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 CHFI exam.
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