- A
DestinationRule with trafficPolicy: tls: mode: ISTIO_MUTUAL
Why wrong: DestinationRule configures traffic policies for a specific host, not namespace-wide mTLS enforcement. PeerAuthentication is the correct resource for namespace-level mTLS.
- B
VirtualService with TLS settings
Why wrong: VirtualService is for traffic routing, not mTLS enforcement.
- C
PeerAuthentication with mode: STRICT in the namespace
Correct. PeerAuthentication defines mTLS settings per namespace or workload. Mode STRICT requires mTLS.
- D
ServiceEntry with mTLS enabled
Why wrong: ServiceEntry is used to add external services to the mesh, not to enforce mTLS within the mesh.
Question 474 of 997
Which Istio Resource Enforces Mutual TLS in a Namespace?
This CKS practice question tests your understanding of minimize microservice vulnerabilities. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 pod runs with a service mesh sidecar (Istio). The team wants to enforce mutual TLS (mTLS) for all traffic between services in the 'production' namespace. Which resource should be applied?
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
✓
PeerAuthentication with mode: STRICT in the namespace
PeerAuthentication with mode: STRICT enforces mutual TLS at the service mesh level by requiring all traffic within the namespace to use TLS certificates for both sides of the connection. This is the correct Istio resource to enforce mTLS for all services in the 'production' namespace, as it sets a namespace-wide policy that overrides any permissive defaults.
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.
- ✗
DestinationRule with trafficPolicy: tls: mode: ISTIO_MUTUAL
Why it's wrong here
DestinationRule configures traffic policies for a specific host, not namespace-wide mTLS enforcement. PeerAuthentication is the correct resource for namespace-level mTLS.
- ✗
VirtualService with TLS settings
Why it's wrong here
VirtualService is for traffic routing, not mTLS enforcement.
- ✓
PeerAuthentication with mode: STRICT in the namespace
Why this is correct
Correct. PeerAuthentication defines mTLS settings per namespace or workload. Mode STRICT requires mTLS.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
ServiceEntry with mTLS enabled
Why it's wrong here
ServiceEntry is used to add external services to the mesh, not to enforce mTLS within the mesh.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the distinction between PeerAuthentication (which enforces mTLS on the server side) and DestinationRule (which configures client-side TLS), leading candidates to mistakenly choose DestinationRule for namespace-wide mTLS enforcement.
Detailed technical explanation
How to think about this question
PeerAuthentication works by configuring the Envoy sidecar proxy to require TLS on inbound connections; when mode: STRICT is set, the proxy rejects any plaintext traffic and only accepts TLS connections with valid client certificates. This is enforced at the network layer via the Envoy filter chain, and the mTLS handshake uses SPIFFE-compliant identities (e.g., spiffe://cluster.local/ns/production/sa/default) to authenticate workloads. In a real-world scenario, if a legacy service without a sidecar is deployed in the namespace, STRICT mode will break its connectivity, so operators must ensure all workloads have sidecars injected before applying this policy.
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 practitioner preparing for the CKS 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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Minimize Microservice Vulnerabilities — study guide chapter
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FAQ
Questions learners often ask
What does this CKS question test?
Minimize Microservice Vulnerabilities — This question tests Minimize Microservice Vulnerabilities — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: PeerAuthentication with mode: STRICT in the namespace — PeerAuthentication with mode: STRICT enforces mutual TLS at the service mesh level by requiring all traffic within the namespace to use TLS certificates for both sides of the connection. This is the correct Istio resource to enforce mTLS for all services in the 'production' namespace, as it sets a namespace-wide policy that overrides any permissive defaults.
What should I do if I get this CKS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
This CKS practice question is part of Courseiva's free CNCF 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 CKS exam.
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