The correct actions are to enable SSH public key authentication only, disable password-based authentication, and apply an access control list to block the offending IP. Disabling password logins eliminates the primary vector for a brute-force attack, as attackers cannot guess credentials when only cryptographic key pairs are accepted—keys that are computationally infeasible to crack. Blocking the specific external IP with an ACL stops the immediate threat while the configuration change takes effect. On the SSCP exam, this scenario tests your understanding of layered defense for remote access, often appearing as a multi-select question where a common trap is choosing to simply increase password complexity instead of removing passwords entirely. Remember the memory tip: “Keys, not words, and block the herd”—meaning use key-based authentication and block the attacking IP to fully mitigate SSH brute force attacks.
SSCP Network and Communications Security Practice Question
This SSCP practice question tests your understanding of network and communications 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 security analyst is reviewing network device logs and finds multiple failed SSH login attempts from a single external IP. Which three actions should the analyst take to mitigate this brute-force attack? (Choose three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Disable password-based authentication for SSH.
Disabling password-based authentication for SSH (Option B) eliminates the primary vector for brute-force attacks, as attackers cannot guess passwords. This forces the use of cryptographic key pairs, which are computationally infeasible to brute-force. Combined with an ACL to block the offending IP (Option C) and enabling only public key authentication (Option D), these three actions directly mitigate the ongoing and future brute-force attempts.
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.
✗
Increase the SSH login timeout.
Why it's wrong here
Longer timeout does not prevent repeated attempts.
✓
Disable password-based authentication for SSH.
Why this is correct
Eliminates the credential guessing attack.
Related concept
Read the scenario before looking for a memorised answer.
✓
Implement an ACL to block the offending IP.
Why this is correct
Blocking the source IP stops the attack.
Related concept
Read the scenario before looking for a memorised answer.
✓
Enable SSH public key authentication only.
Why this is correct
Public key authentication is resistant to brute-force.
Related concept
Read the scenario before looking for a memorised answer.
✗
Change the SSH port to a non-standard port.
Why it's wrong here
This is security by obscurity and not effective.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose 'Change the SSH port to a non-standard port' (Option E) thinking it provides real security, but the SSCP exam expects you to recognize that security by obscurity is not a valid mitigation for an active brute-force attack.
Detailed technical explanation
How to think about this question
SSH public key authentication uses asymmetric cryptography (RSA, ECDSA, or Ed25519) where the server verifies a client's possession of the private key without transmitting it. Blocking the offending IP via an ACL at the network layer (e.g., using an extended ACL on a router or firewall) drops all packets from that source, immediately halting the attack. Disabling password authentication in sshd_config (setting 'PasswordAuthentication no') forces all clients to use key-based authentication, which is resistant to dictionary and brute-force attacks.
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 developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
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.
Network and Communications Security — This question tests Network and Communications Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Disable password-based authentication for SSH. — Disabling password-based authentication for SSH (Option B) eliminates the primary vector for brute-force attacks, as attackers cannot guess passwords. This forces the use of cryptographic key pairs, which are computationally infeasible to brute-force. Combined with an ACL to block the offending IP (Option C) and enabling only public key authentication (Option D), these three actions directly mitigate the ongoing and future brute-force attempts.
What should I do if I get this SSCP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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