- A
openssl genrsa -out key.pem 2048 && openssl req -new -key key.pem -out cert.pem
Why wrong: This generates a CSR, not a self-signed certificate.
- B
openssl x509 -req -in req.pem -signkey key.pem -out cert.pem
Why wrong: This signs a CSR with a private key, but does not generate a key.
- C
openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365 -nodes
This command creates a self-signed certificate valid for 365 days.
- D
openssl ca -in req.pem -out cert.pem
Why wrong: This requires a CA setup, not self-signed.
Question 922 of 981
XK0-005 Security Practice Question
This XK0-005 practice question tests your understanding of security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 technician needs to create a self-signed certificate and private key for a web server. Which OpenSSL command should be used?
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
Option C is correct because the `openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365 -nodes` command generates a new RSA 2048-bit private key and immediately creates a self-signed X.509 certificate in a single step. The `-x509` flag tells OpenSSL to output a self-signed certificate instead of a certificate signing request (CSR), and `-nodes` ensures the private key is not encrypted with a passphrase, which is typical for a web server that must start without manual intervention.
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.
- ✗
openssl genrsa -out key.pem 2048 && openssl req -new -key key.pem -out cert.pem
Why it's wrong here
This generates a CSR, not a self-signed certificate.
- ✗
openssl x509 -req -in req.pem -signkey key.pem -out cert.pem
Why it's wrong here
This signs a CSR with a private key, but does not generate a key.
- ✓
openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365 -nodes
Why this is correct
This command creates a self-signed certificate valid for 365 days.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
openssl ca -in req.pem -out cert.pem
Why it's wrong here
This requires a CA setup, not self-signed.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the `req -new` command (which creates a CSR) with the `req -x509` command (which creates a self-signed certificate), leading them to choose Option A, which only produces a CSR, not a usable certificate for a web server.
Detailed technical explanation
How to think about this question
The `-newkey` option in `openssl req` generates a new private key and CSR simultaneously; when combined with `-x509`, it bypasses CSR generation and directly produces a self-signed certificate. The `-nodes` option (no DES) prevents OpenSSL from encrypting the private key with a symmetric cipher, which is essential for automated web server startups where no passphrase can be entered. In real-world scenarios, self-signed certificates are used in development or internal networks, but browsers will flag them as untrusted because they lack a chain of trust to a public CA.
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 practitioner preparing for the XK0-005 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
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 |
What to study next
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FAQ
Questions learners often ask
What does this XK0-005 question test?
Security — This question tests Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365 -nodes — Option C is correct because the `openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365 -nodes` command generates a new RSA 2048-bit private key and immediately creates a self-signed X.509 certificate in a single step. The `-x509` flag tells OpenSSL to output a self-signed certificate instead of a certificate signing request (CSR), and `-nodes` ensures the private key is not encrypted with a passphrase, which is typical for a web server that must start without manual intervention.
What should I do if I get this XK0-005 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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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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