- A
Set PermitRootLogin to no in /etc/ssh/sshd_config to prevent root login.
Disabling root login eliminates direct SSH access to the root account, a common target.
- B
Change the SSH port to a non-standard port to evade automated attacks.
Why wrong: Changing the port is not a strong security measure; attackers can scan for open ports.
- C
Disable password authentication and force key-based authentication only.
Why wrong: While secure, this may not be immediately feasible if users rely on passwords; it's a longer-term solution.
- D
Increase MaxAuthTries to allow more retries before disconnection.
Why wrong: Increasing retries would make brute-force attacks easier, not harder.
- E
Install and configure fail2ban to block IPs after multiple failed attempts.
fail2ban can automatically block IPs that exhibit brute-force behavior.
XK0-005 Practice Question: Refer to the exhibit
This XK0-005 practice question tests your understanding of xk0-005 exam topics. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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. A security analyst notices repeated failed SSH login attempts from multiple IP addresses. Which two actions would best mitigate this brute-force attack? (Choose two.)
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
Set PermitRootLogin to no in /etc/ssh/sshd_config to prevent root login.
The logs show failed password attempts for root and invalid users from different IPs, indicating a brute-force attack. Using fail2ban can automatically block IPs after repeated failures. Disabling root login over SSH eliminates a common target. Option B (changing the port) is security through obscurity and not a robust mitigation. Option C (disabling password authentication) might break legitimate users and is excessive without key-based auth. Option E (increasing MaxAuthTries) would make the attack easier.
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.
- ✓
Set PermitRootLogin to no in /etc/ssh/sshd_config to prevent root login.
Why this is correct
Disabling root login eliminates direct SSH access to the root account, a common target.
Related concept
Standard ACLs match source addresses.
- ✗
Change the SSH port to a non-standard port to evade automated attacks.
Why it's wrong here
Changing the port is not a strong security measure; attackers can scan for open ports.
- ✗
Disable password authentication and force key-based authentication only.
Why it's wrong here
While secure, this may not be immediately feasible if users rely on passwords; it's a longer-term solution.
- ✗
Increase MaxAuthTries to allow more retries before disconnection.
Why it's wrong here
Increasing retries would make brute-force attacks easier, not harder.
- ✓
Install and configure fail2ban to block IPs after multiple failed attempts.
Why this is correct
fail2ban can automatically block IPs that exhibit brute-force behavior.
Related concept
Standard ACLs match source addresses.
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.
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FAQ
Questions learners often ask
What does this XK0-005 question test?
Standard ACLs match source addresses.
What is the correct answer to this question?
The correct answer is: Set PermitRootLogin to no in /etc/ssh/sshd_config to prevent root login. — The logs show failed password attempts for root and invalid users from different IPs, indicating a brute-force attack. Using fail2ban can automatically block IPs after repeated failures. Disabling root login over SSH eliminates a common target. Option B (changing the port) is security through obscurity and not a robust mitigation. Option C (disabling password authentication) might break legitimate users and is excessive without key-based auth. Option E (increasing MaxAuthTries) would make the attack easier.
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
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.
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