XK0-006 Security Practice Question
An administrator needs to generate a self-signed certificate valid for 365 days with a 2048-bit RSA key. Which OpenSSL command correctly creates both the private key and certificate in one step?
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
✓
openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365 -nodes
The 'req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365 -nodes' generates a self-signed certificate with a key. Other commands either miss -x509, -newkey, or use wrong options.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365 -nodes
Why this is correct
Single command that generates both key and self-signed certificate.
- ✗
openssl x509 -req -in req.pem -signkey key.pem -out cert.pem -days 365
Why it's wrong here
Requires existing CSR and key, not one step.
- ✗
openssl ca -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365
Why it's wrong here
Used for CA operations, not self-signed.
- ✗
openssl genrsa -out key.pem 2048 && openssl req -new -x509 -key key.pem -out cert.pem -days 365
Why it's wrong here
Valid but two steps; not one step.
Quick reference
Asymmetric Encryption Algorithm Comparison
| Algorithm | Key Exchange | Signatures | Equivalent Security Key | Notes |
|---|---|---|---|---|
| RSA-3072 | Yes | Yes | 128-bit | Widely deployed; slow for bulk data |
| ECDSA P-256 | No | Yes | 128-bit | Fast signatures; standard TLS certs |
| ECDH / ECDHE | Yes | No | 128-bit | Perfect forward secrecy in TLS 1.3 |
| DH / DHE | Yes | No | 128-bit (3072-bit key) | Replaced by ECDHE in modern TLS |
| Ed25519 | No | Yes | ~128-bit | SSH keys, modern PKI |
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This XK0-006 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 XK0-006 exam.