The answer is TLS, as it is the only protocol among common options that provides both encryption for confidentiality and a Message Authentication Code (MAC) for integrity, making it the definitive choice for secure communication over an untrusted network. TLS establishes an encrypted tunnel using symmetric keys exchanged via asymmetric cryptography, while its MAC ensures that data has not been tampered with during transit, addressing the core requirements of the CAS-004 exam objective on secure network architecture. On the CompTIA SecurityX exam, this question tests your ability to distinguish between protocols like IPsec, SSH, and TLS, with a common trap being to choose IPsec for site-to-site links when the scenario specifies internal systems communicating over an untrusted network—TLS is preferred here for its lightweight, application-layer integration. A helpful memory tip is to think of TLS as the “two-in-one” protocol: it locks the data (confidentiality) and seals it (integrity), ensuring nothing is read or changed in transit.
CAS-004 Security Engineering Practice Question
This CAS-004 practice question tests your understanding of security engineering. 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 engineer is designing a secure communication channel between two internal systems over an untrusted network. Which protocol should be used to ensure both confidentiality and integrity of data in transit?
Why wrong: SSH is used for secure remote administration, not typically for system-to-system communication channels.
B
TLS
TLS provides encryption (confidentiality) and MAC (integrity), suitable for any TCP-based communication.
C
HTTPS
Why wrong: HTTPS is HTTP over TLS, but the question does not specify web traffic; TLS is the underlying protocol.
D
IPsec
Why wrong: IPsec can also provide confidentiality and integrity, but it is more complex and typically used for VPNs; TLS is simpler for direct system-to-system communication.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
TLS
TLS provides encryption for confidentiality and MAC for integrity, making it the best choice for secure communication over an untrusted network.
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.
✗
SSH
Why it's wrong here
SSH is used for secure remote administration, not typically for system-to-system communication channels.
✓
TLS
Why this is correct
TLS provides encryption (confidentiality) and MAC (integrity), suitable for any TCP-based communication.
Related concept
Read the scenario before looking for a memorised answer.
✗
HTTPS
Why it's wrong here
HTTPS is HTTP over TLS, but the question does not specify web traffic; TLS is the underlying protocol.
✗
IPsec
Why it's wrong here
IPsec can also provide confidentiality and integrity, but it is more complex and typically used for VPNs; TLS is simpler for direct system-to-system communication.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 CAS-004 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.
What to study next
Got this wrong? Here's your next step.
Identify which CAS-004 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Security Engineering — This question tests Security Engineering — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: TLS — TLS provides encryption for confidentiality and MAC for integrity, making it the best choice for secure communication over an untrusted network.
What should I do if I get this CAS-004 question wrong?
Identify which CAS-004 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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