The answer is mutual TLS (mTLS), an API gateway, and data encryption in transit. Mutual TLS ensures that both the sending and receiving microservices cryptographically authenticate each other before any data exchange, preventing man-in-the-middle attacks and unauthorized service impersonation. An API gateway acts as a centralized policy enforcement point, handling authentication, rate limiting, and traffic filtering for all inter-service communication, which simplifies security management across distributed services. On the CompTIA SecurityX CAS-004 exam, this question tests your ability to distinguish runtime controls from development or storage controls—common traps include selecting static code analysis (a development-time check) or data encryption at rest (which protects stored data, not data in motion). Remember the memory tip: “mTLS for trust, Gateway for guard, and Transit for transport”—these three controls directly secure the communication channel between services, not the code or the database.
CAS-004 Practice Question: Application Environment, Configuration and Security
This CAS-004 practice question tests your understanding of application environment, configuration and 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 company is migrating its monolithic application to a microservices architecture. The security team wants to implement controls to protect inter-service communication and ensure data integrity. Which THREE security controls should be implemented? (Select THREE.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Deploy an API gateway to enforce rate limiting and authentication
Mutual TLS ensures both services authenticate each other. An API gateway provides a central point for enforcing security policies. Static code analysis is a development-time control, not runtime. Data encryption at rest protects stored data, not inter-service communication. Container orchestration is a management tool, not a direct security control for inter-service communication.
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 data at rest using AES-256
Why it's wrong here
Data at rest encryption protects stored data, not inter-service communication.
✓
Deploy an API gateway to enforce rate limiting and authentication
Why this is correct
An API gateway centralizes security enforcement for microservices.
Related concept
Read the scenario before looking for a memorised answer.
✓
Implement mutual TLS (mTLS) for service-to-service authentication
Why this is correct
mTLS ensures both ends verify identity, securing communication.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use a container orchestration platform to manage service discovery
Why it's wrong here
Orchestration manages deployment and scaling, not a direct security control for communication.
✗
Conduct static code analysis on all microservices
Why it's wrong here
Static analysis is a development-time control, not for runtime inter-service security.
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.
Application Environment, Configuration and Security — This question tests Application Environment, Configuration and Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Deploy an API gateway to enforce rate limiting and authentication — Mutual TLS ensures both services authenticate each other. An API gateway provides a central point for enforcing security policies. Static code analysis is a development-time control, not runtime. Data encryption at rest protects stored data, not inter-service communication. Container orchestration is a management tool, not a direct security control for inter-service communication.
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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