CISSP Communication and Network Security Practice Question
A company is implementing TLS 1.3 to secure web communications. Which of the following features is unique to TLS 1.3 compared to earlier versions?
⚠ Common exam trap
Candidates often confuse 'mandatory forward secrecy' with optional forward secrecy in earlier TLS versions, or mistakenly think RSA key exchange is still supported in TLS 1.3.
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
✓
Mandatory forward secrecy using ephemeral Diffie-Hellman
TLS 1.3 (RFC 8446) mandates forward secrecy by requiring ephemeral Diffie-Hellman (DHE or ECDHE) key exchange for all handshakes. This ensures that session keys are never derived from long-term static keys, so compromising the server's private key does not compromise past session keys. Earlier TLS versions allowed static RSA key exchange, which lacks forward secrecy.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Mandatory forward secrecy using ephemeral Diffie-Hellman
Why this is correct
TLS 1.3 requires ephemeral key exchanges (DHE or ECDHE) providing forward secrecy.
- ✗
Support for RSA key exchange
Why it's wrong here
RSA key exchange is removed in TLS 1.3 due to lack of forward secrecy.
- ✗
Only server-side authentication
Why it's wrong here
TLS 1.3 supports mutual authentication, but it is not mandatory.
- ✗
Use of RC4 for encryption
Why it's wrong here
RC4 is deprecated and removed in TLS 1.3.
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 |
Go deeper
Related to this question
About these practice questions
This CISSP question is part of Courseiva's 747-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.