CAS-004 Security Engineering Practice Question
A security engineer is hardening an SSH server. The policy requires disabling all legacy algorithms and using only modern, secure cryptography. Which THREE of the following configurations should the engineer apply?
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 HMAC algorithms to use only SHA-2 or stronger.
Key-based authentication only is more secure than passwords. Disabling password authentication prevents brute-force attacks. Restricting key exchange to curve25519 ensures strong forward secrecy. Enabling root login with password is insecure. Using SHA-1 for HMAC is weak.
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 HMAC algorithms to use only SHA-2 or stronger.
Why this is correct
SHA-1 is deprecated; SHA-2 or newer should be used.
- ✗
Allow only SSH protocol version 1 for compatibility.
Why it's wrong here
SSHv1 is obsolete and insecure.
- ✗
Enable root login with password for administrative convenience.
Why it's wrong here
Root login with password is a security risk.
- ✓
Disable password authentication and allow only key-based authentication.
Why this is correct
Key-based authentication is more secure and recommended.
- ✓
Restrict key exchange algorithms to curve25519-sha256.
Why this is correct
Curve25519 is a modern, secure key exchange algorithm.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CAS-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 CAS-005 exam.