This LFCS practice question tests your understanding of operation of running systems. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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. What is the most likely security issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
SSH service is not running.
Why wrong: The service is logging, so it is running.
The root account is disabled.
Why wrong: If disabled, attempts would show 'invalid user' or similar, not 'failed password'.
Someone is attempting to brute-force the root password.
Repeated failed attempts from same IP indicate a brute-force attack.
The firewall is blocking SSH.
Why wrong: If blocked, no log entries would appear.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Someone is attempting to brute-force the root password.
The exhibit shows multiple failed SSH login attempts for the root user from the same IP address in quick succession, as seen in the auth.log or secure log entries. This pattern indicates a brute-force attack, where an attacker systematically tries different passwords to gain unauthorized root access. Option C is correct because the repeated 'Failed password for root' messages are the hallmark of a brute-force attempt.
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.
SSH service is not running.
Why it's wrong here
The service is logging, so it is running.
The root account is disabled.
Why it's wrong here
If disabled, attempts would show 'invalid user' or similar, not 'failed password'.
Someone is attempting to brute-force the root password.
Why this is correct
Repeated failed attempts from same IP indicate a brute-force attack.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
The firewall is blocking SSH.
Why it's wrong here
If blocked, no log entries would appear.
Common exam traps
The trap here is that candidates may see 'SSH' and 'root' and incorrectly assume the service is down or the account is disabled, rather than recognizing the pattern of repeated failed login attempts as a brute-force attack.
Trap categories for this question
Similar concept trap
If disabled, attempts would show 'invalid user' or similar, not 'failed password'.
Command / output trap
If disabled, attempts would show 'invalid user' or similar, not 'failed password'.
Detailed technical explanation
SSH brute-force attacks typically target the root account because it has universal privileges and a known username. Tools like Hydra or Medusa automate password guessing, and systems often log these attempts in /var/log/auth.log or /var/log/secure. Mitigation strategies include disabling root login via SSH (PermitRootLogin no in sshd_config), using key-based authentication, and implementing fail2ban or rate-limiting with iptables to block repeated failed attempts.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Operation of Running Systems — This question tests Operation of Running Systems — Read the scenario before looking for a memorised answer..
The correct answer is: Someone is attempting to brute-force the root password. — The exhibit shows multiple failed SSH login attempts for the root user from the same IP address in quick succession, as seen in the auth.log or secure log entries. This pattern indicates a brute-force attack, where an attacker systematically tries different passwords to gain unauthorized root access. Option C is correct because the repeated 'Failed password for root' messages are the hallmark of a brute-force attempt.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This LFCS practice question is part of Courseiva's free Linux Foundation 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 LFCS exam.
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