- A
Encrypt email
Why wrong: Email encryption requires 'emailProtection' EKU.
- B
Authenticate a TLS server
The serverAuth EKU is specifically for TLS server authentication.
- C
Sign code
Why wrong: Code signing requires the 'codeSigning' EKU.
- D
Issue subordinate CA certificates
Why wrong: Issuing CA certificates requires the 'keyCertSign' key usage and appropriate EKU.
Question 101 of 1,000
SSCP Cryptography Practice Question
This SSCP practice question tests your understanding of cryptography. 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 certificate authority (CA) issues a certificate with the extended key usage (EKU) extension specifying 'serverAuth'. Which of the following is this certificate allowed to do?
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
✓
Authenticate a TLS server
The Extended Key Usage (EKU) extension specifies the intended purpose of a certificate. The 'serverAuth' OID (1.3.6.1.5.5.7.3.1) explicitly permits the certificate to be used for authenticating a TLS server during the SSL/TLS handshake, such as in HTTPS. This is defined in RFC 5280 and is enforced by TLS clients to ensure the certificate is used only for its designated purpose.
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.
- ✗
Encrypt email
Why it's wrong here
Email encryption requires 'emailProtection' EKU.
- ✓
Authenticate a TLS server
Why this is correct
The serverAuth EKU is specifically for TLS server authentication.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Sign code
Why it's wrong here
Code signing requires the 'codeSigning' EKU.
- ✗
Issue subordinate CA certificates
Why it's wrong here
Issuing CA certificates requires the 'keyCertSign' key usage and appropriate EKU.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that any certificate can be used for any purpose, but the trap here is that the EKU extension strictly limits the certificate's intended use, and candidates must know the specific OIDs and their mappings to common tasks like server authentication, email encryption, and code signing.
Detailed technical explanation
How to think about this question
Under the hood, the EKU extension is a critical component of certificate path validation; TLS clients (like browsers) check that the server's certificate contains the 'serverAuth' EKU before completing the handshake. A real-world scenario where this matters is when a compromised or misissued certificate with 'serverAuth' is used to impersonate a legitimate server, but it cannot be used for other purposes like signing malware or encrypting emails, limiting the blast radius. The EKU is enforced by applications, not by the CA itself, so a certificate with 'serverAuth' could technically be used for other purposes if the client ignores the extension, but secure implementations reject such misuse.
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.
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FAQ
Questions learners often ask
What does this SSCP question test?
Cryptography — This question tests Cryptography — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Authenticate a TLS server — The Extended Key Usage (EKU) extension specifies the intended purpose of a certificate. The 'serverAuth' OID (1.3.6.1.5.5.7.3.1) explicitly permits the certificate to be used for authenticating a TLS server during the SSL/TLS handshake, such as in HTTPS. This is defined in RFC 5280 and is enforced by TLS clients to ensure the certificate is used only for its designated purpose.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jul 4, 2026
This SSCP practice question is part of Courseiva's free ISC2 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 SSCP exam.
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