- A
Implement a service mesh with mutual TLS (mTLS) and automatic certificate management.
Service mesh provides automated mTLS, encryption, and mutual authentication with low operational overhead.
- B
Deploy IPsec tunnels between each pair of services using pre-shared keys.
Why wrong: IPsec tunnels are static and do not scale with dynamic microservices.
- C
Establish a site-to-site VPN between the Kubernetes cluster and the legacy network, and route all service traffic through the VPN.
Why wrong: VPNs are too coarse for microservices and introduce latency.
- D
Configure each service to use TLS with self-signed certificates, and distribute the CA certificate to all services.
Why wrong: Self-signed certificates require manual distribution and renewal, increasing overhead.
CAS-004 Security Architecture Practice Question
This CAS-004 practice question tests your understanding of security architecture. 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 from a legacy three-tier architecture to a microservices architecture on Kubernetes. The security team wants to ensure that service-to-service communication is encrypted and mutually authenticated. Which approach best meets these requirements with minimal operational overhead?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"best"Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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
Implement a service mesh with mutual TLS (mTLS) and automatic certificate management.
A service mesh with mutual TLS (mTLS) and automatic certificate management is the correct approach because it provides encrypted, mutually authenticated service-to-service communication with minimal operational overhead. The service mesh (e.g., Istio, Linkerd) transparently intercepts traffic via sidecar proxies, handles mTLS handshakes, and automates certificate issuance and rotation, eliminating the need for manual key distribution or application-level changes.
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.
- ✓
Implement a service mesh with mutual TLS (mTLS) and automatic certificate management.
Why this is correct
Service mesh provides automated mTLS, encryption, and mutual authentication with low operational overhead.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Deploy IPsec tunnels between each pair of services using pre-shared keys.
Why it's wrong here
IPsec tunnels are static and do not scale with dynamic microservices.
- ✗
Establish a site-to-site VPN between the Kubernetes cluster and the legacy network, and route all service traffic through the VPN.
Why it's wrong here
VPNs are too coarse for microservices and introduce latency.
- ✗
Configure each service to use TLS with self-signed certificates, and distribute the CA certificate to all services.
Why it's wrong here
Self-signed certificates require manual distribution and renewal, increasing overhead.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may choose IPsec or VPN solutions because they are familiar with network-layer encryption, but they fail to recognize that these approaches do not scale to the dynamic, ephemeral nature of microservices and introduce prohibitive operational overhead compared to a service mesh's automated mTLS.
Detailed technical explanation
How to think about this question
In a service mesh, each service instance is paired with a sidecar proxy (e.g., Envoy) that handles mTLS using X.509 certificates issued by a built-in certificate authority (e.g., Istio's Citadel). The mesh automatically rotates certificates (typically every 24 hours) and enforces SPIFFE-based identities, ensuring that even if a pod is compromised, the attacker cannot impersonate another service without a valid certificate. This approach is critical in zero-trust architectures where network boundaries are no longer trusted.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation 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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FAQ
Questions learners often ask
What does this CAS-004 question test?
Security Architecture — This question tests Security Architecture — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Implement a service mesh with mutual TLS (mTLS) and automatic certificate management. — A service mesh with mutual TLS (mTLS) and automatic certificate management is the correct approach because it provides encrypted, mutually authenticated service-to-service communication with minimal operational overhead. The service mesh (e.g., Istio, Linkerd) transparently intercepts traffic via sidecar proxies, handles mTLS handshakes, and automates certificate issuance and rotation, eliminating the need for manual key distribution or application-level changes.
What should I do if I get this CAS-004 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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: Jun 11, 2026
This CAS-004 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-004 exam.
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