Question 216 of 510

Security →hardMultiple ChoiceObjective-mapped

Quick Answer

The answer is that the root account is not subject to pam_tally2 without the 'even_deny_root' option, so the lockout stems from another mechanism. By default, pam_tally2 only tracks and denies regular user accounts after failed login attempts; the root account is explicitly exempt unless the 'even_deny_root' flag is added to the configuration line. Since the administrator is likely logging in as root, the observed lockout after 300 seconds is not from pam_tally2 but from a separate control like sshd's MaxAuthTries or a service such as fail2ban. On the CompTIA Linux+ XK0-005 exam, this tests your understanding of PAM module behavior and the common trap of assuming pam_tally2 applies universally. A key memory tip: "Root is root—pam_tally2 won't boot it without 'even_deny_root'."

XK0-005 Security Practice Question

This XK0-005 practice question tests your understanding of security. 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.

A Linux server in a DMZ is experiencing intermittent SSH lockouts. The /var/log/secure shows repeated failed login attempts from multiple IP addresses, but then suddenly the administrator cannot SSH in even with correct credentials. The administrator suspects a brute-force protection mechanism. The server uses PAM with pam_tally2 for login counting. The administrator checks /etc/pam.d/sshd and sees: auth required pam_tally2.so deny=3 unlock_time=300 onerr=succeed file=/var/log/tallylog. What is the most likely reason the administrator is locked out even after 5 minutes?

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.

Question 1hardmultiple choice

Full question →

A
The SSH server is not configured with UsePAM yes, so pam_tally2 is not applied
Why wrong: If PAM is not used, sshd would not check pam_tally2 at all, but the log shows failures, so PAM is active.
B
The tallylog file has incorrect permissions, preventing pam_tally2 from reading the count
Why wrong: This would be logged as an error, but the admin sees lockouts from multiple IPs, indicating the module is working.
C
The root account is not subject to pam_tally2 without the 'even_deny_root' option, so the lockout is from another mechanism
By default, pam_tally2 excludes root unless even_deny_root is set. The administrator is likely using root, and the lockout is caused by something else like fail2ban or iptables.
D
The DenyHosts service is running and blocks IPs after too many failures
Why wrong: While possible, the question centers on pam_tally2; the most likely direct reason given the config is root exclusion.

Full breakdown with real-world context →

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

✓

The root account is not subject to pam_tally2 without the 'even_deny_root' option, so the lockout is from another mechanism

Option C is correct because pam_tally2 does not apply to the root account unless the 'even_deny_root' option is explicitly added to the pam_tally2 configuration line. Since the administrator is likely logging in as root (or the root account is being targeted), the lockout observed is not from pam_tally2 but from another mechanism such as sshd's own MaxAuthTries or a separate service like fail2ban. The configuration shown only denies regular users after 3 failures and unlocks after 300 seconds, but root remains unaffected by this rule.

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.

✗
The SSH server is not configured with UsePAM yes, so pam_tally2 is not applied
Why it's wrong here
If PAM is not used, sshd would not check pam_tally2 at all, but the log shows failures, so PAM is active.
✗
The tallylog file has incorrect permissions, preventing pam_tally2 from reading the count
Why it's wrong here
This would be logged as an error, but the admin sees lockouts from multiple IPs, indicating the module is working.
✓
The root account is not subject to pam_tally2 without the 'even_deny_root' option, so the lockout is from another mechanism
Why this is correct
By default, pam_tally2 excludes root unless even_deny_root is set. The administrator is likely using root, and the lockout is caused by something else like fail2ban or iptables.
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 DenyHosts service is running and blocks IPs after too many failures
Why it's wrong here
While possible, the question centers on pam_tally2; the most likely direct reason given the config is root exclusion.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates assume pam_tally2 applies equally to all users, including root, without realizing the default exemption for root and the need for the 'even_deny_root' option.

Trap categories for this question

Command / output trap
If PAM is not used, sshd would not check pam_tally2 at all, but the log shows failures, so PAM is active.

Detailed technical explanation

How to think about this question

pam_tally2 maintains per-user login failure counts in a file (default /var/log/tallylog). By default, the root account is exempt from the deny threshold; to enforce lockout for root, the 'even_deny_root' option must be added. Additionally, the 'unlock_time' parameter sets the lockout duration in seconds, but for root without even_deny_root, the count is still tracked but never triggers denial. In real-world scenarios, administrators often forget this nuance and assume root is protected, leading to unexpected lockout behavior from other mechanisms like sshd's MaxAuthTries (default 6) or external tools like fail2ban.

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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.

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.

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FAQ

Questions learners often ask

What does this XK0-005 question test?

Security — This question tests Security — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: The root account is not subject to pam_tally2 without the 'even_deny_root' option, so the lockout is from another mechanism — Option C is correct because pam_tally2 does not apply to the root account unless the 'even_deny_root' option is explicitly added to the pam_tally2 configuration line. Since the administrator is likely logging in as root (or the root account is being targeted), the lockout observed is not from pam_tally2 but from another mechanism such as sshd's own MaxAuthTries or a separate service like fail2ban. The configuration shown only denies regular users after 3 failures and unlocks after 300 seconds, but root remains unaffected by this rule.

What should I do if I get this XK0-005 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 25, 2026

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This XK0-005 practice question is part of Courseiva's free CompTIA 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 XK0-005 exam.