- A
S/MIME
S/MIME uses certificates to encrypt and sign emails.
- B
SSL/TLS
Why wrong: SSL/TLS secures the transport channel, not the email content end-to-end.
- C
PGP/GPG
PGP/GPG provides encryption and signing using a web of trust.
- D
SSH
Why wrong: SSH is for secure remote access, not email.
- E
IPsec
Why wrong: IPsec secures IP communications, not email.
Question 699 of 1,000
CISSP Communication and Network Security Practice Question
This CISSP practice question tests your understanding of communication and network 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 security analyst is evaluating secure email protocols. Which TWO of the following provide both encryption and digital signing of email messages?
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
✓
S/MIME
S/MIME (Secure/Multipurpose Internet Mail Extensions) is a standard for public key encryption and digital signing of MIME data. It uses X.509 certificates for key exchange and provides both confidentiality (encryption) and non-repudiation (digital signing) for email messages, making it a correct choice.
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.
- ✓
S/MIME
Why this is correct
S/MIME uses certificates to encrypt and sign emails.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
SSL/TLS
Why it's wrong here
SSL/TLS secures the transport channel, not the email content end-to-end.
- ✓
PGP/GPG
Why this is correct
PGP/GPG provides encryption and signing using a web of trust.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
SSH
Why it's wrong here
SSH is for secure remote access, not email.
- ✗
IPsec
Why it's wrong here
IPsec secures IP communications, not email.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is confusing transport-layer security (SSL/TLS) with end-to-end message security; candidates often select SSL/TLS because it encrypts email in transit, but it does not provide digital signing or protect the message after delivery.
Detailed technical explanation
How to think about this question
S/MIME relies on a hierarchical public key infrastructure (PKI) with X.509 certificates, where the sender signs the message digest with their private key and optionally encrypts the symmetric session key with the recipient's public key. PGP/GPG uses a web of trust model instead of a centralized CA, employing RSA or DSA for signing and AES or CAST5 for symmetric encryption. Both protocols embed cryptographic metadata in the email headers (e.g., Content-Type: application/pkcs7-mime) to signal signed or encrypted content.
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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Communication and Network Security — study guide chapter
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FAQ
Questions learners often ask
What does this CISSP question test?
Communication and Network Security — This question tests Communication and Network Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: S/MIME — S/MIME (Secure/Multipurpose Internet Mail Extensions) is a standard for public key encryption and digital signing of MIME data. It uses X.509 certificates for key exchange and provides both confidentiality (encryption) and non-repudiation (digital signing) for email messages, making it a correct choice.
What should I do if I get this CISSP 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
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Last reviewed: Jul 4, 2026
This CISSP 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 CISSP exam.
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