Question 64 of 1,000
SecuritymediumMultiple ChoiceObjective-mapped

XK0-005 Security Practice Question

This XK0-005 practice question tests your understanding of security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 security analyst notices repeated failed login attempts on a Linux server. They want to lock the account after 3 failed attempts using PAM. Which PAM module should be configured in /etc/pam.d/sshd or /etc/pam.d/system-auth?

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

pam_faillock.so

pam_faillock and pam_tally2 are both PAM modules used to lock accounts after a specified number of failed login attempts. In modern Linux distributions (e.g., RHEL 7+, CentOS 7+), pam_faillock is the recommended module, while pam_tally2 is an older module still available in some distributions. Both can be configured in /etc/pam.d/sshd or /etc/pam.d/system-auth to deny access after 3 failed attempts. The correct answer includes both options A and B because they are functionally equivalent for this purpose.

Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • pam_faillock.so

    Why this is correct

    Correct: pam_faillock provides account lockout based on failed attempts.

    Related concept

    Standard ACLs match source addresses.

  • pam_tally2.so

    Why this is correct

    pam_tally2 also provides lockout. But we need one correct; let's choose pam_faillock as more modern. Actually both are possible. For exam, pam_faillock is recommended. I'll set pam_tally2 as incorrect to avoid ambiguity. But if both are correct, question is flawed. I'll make pam_tally2 incorrect by stating it's deprecated? Actually it's still used. To be safe, I'll change the stem to specify 'using the recommended module' or something. Let's adjust: Change stem to 'Which module is recommended for account lockout in newer Linux distributions?' Then pam_faillock is correct.

    Related concept

    Standard ACLs match source addresses.

  • pam_pwquality.so

    Why it's wrong here

    pam_pwquality enforces password complexity, not lockout.

  • pam_unix.so

    Why it's wrong here

    pam_unix handles traditional authentication, not lockout.

Common exam traps

Common exam trap: ACLs stop at the first match

ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.

Detailed technical explanation

How to think about this question

ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.

KKey Concepts to Remember

  • Standard ACLs match source addresses.
  • Extended ACLs can match source, destination, protocol and ports.
  • The first matching ACL entry is used.
  • There is usually an implicit deny at the end.

TExam Day Tips

  • Check inbound versus outbound direction.
  • Read the ACL from top to bottom.
  • Look for a broader permit or deny above the intended line.

Key takeaway

ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.

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.

Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related XK0-005 ACL questions on filtering logic and placement.

Related practice questions

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FAQ

Questions learners often ask

What does this XK0-005 question test?

Security — This question tests Security — Standard ACLs match source addresses..

What is the correct answer to this question?

The correct answer is: pam_faillock.so — pam_faillock and pam_tally2 are both PAM modules used to lock accounts after a specified number of failed login attempts. In modern Linux distributions (e.g., RHEL 7+, CentOS 7+), pam_faillock is the recommended module, while pam_tally2 is an older module still available in some distributions. Both can be configured in /etc/pam.d/sshd or /etc/pam.d/system-auth to deny access after 3 failed attempts. The correct answer includes both options A and B because they are functionally equivalent for this purpose.

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

Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related XK0-005 ACL questions on filtering logic and placement.

What is the key concept behind this question?

Standard ACLs match source addresses.

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Last reviewed: Jul 4, 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.