CAS-004 Security Engineering Practice Question
A security engineer is configuring a TLS 1.3 connection between a web server and client. Which feature is unique to TLS 1.3 and provides reduced latency for returning clients?
⚠ Common exam trap
CAS-005 often tests whether candidates confuse forward secrecy (a confidentiality property present since TLS 1.2) with 0-RTT (a TLS 1.3-only latency feature), so pick 0-RTT when the question mentions reduced latency for returning clients.
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
✓
0-RTT
0-RTT (zero round-trip time) resumption is a TLS 1.3 feature that lets a returning client send application data in the first flight using a previously established session ticket, eliminating the round trip needed for a full handshake. This reduces latency for repeat connections. It is unique to TLS 1.3 and not available in TLS 1.2.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Cipher suite negotiation
Why it's wrong here
Cipher suite negotiation exists in TLS 1.2 and earlier as well, so it is not unique to 1.3 and adds no returning-client latency reduction. It matters when restricting algorithms for compliance, not for resumption performance.
- ✓
0-RTT
Why this is correct
0-RTT allows a returning client to send application data in the first flight using a previously established pre-shared key, eliminating a round trip. This satisfies the reduced-latency requirement unique to TLS 1.3, though it carries replay risk that deployments must mitigate.
- ✗
Forward secrecy
Why it's wrong here
Forward secrecy protects past session keys if a long-term key is later compromised; it does not shorten the handshake. It is the correct property when the requirement is confidentiality of recorded traffic after key compromise, not reduced latency for returning clients.
- ✗
Mutual authentication
Why it's wrong here
Mutual authentication requires both parties to present certificates, adding a round trip and handshake data rather than removing one. It is chosen where the client must also prove its identity, such as internal service-to-service or zero-trust mTLS deployments.
Go deeper
Related to this question
About these practice questions
This CAS-005 question is part of Courseiva's 973-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 and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This CAS-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 CAS-005 exam.