- A
PeerAuthentication with mtls.mode: STRICT in the namespace
PeerAuthentication with mtls.mode: STRICT enforces mTLS for all services in the namespace.
- B
VirtualService with tls mode
Why wrong: VirtualService is used for traffic routing, not TLS enforcement.
- C
DestinationRule with trafficPolicy.tls.mode: ISTIO_MUTUAL
Why wrong: DestinationRule configures client-side TLS settings, but does not enforce peer authentication across the namespace.
- D
ServiceEntry for external services
Why wrong: ServiceEntry is for external services, not internal mTLS enforcement.
Question 128 of 997
Enforce Mutual TLS in Istio with PeerAuthentication
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.
An administrator wants to enforce mTLS between all services in the 'mesh' namespace using Istio. Which resource should be applied to require mutual TLS for all workloads in that namespace?
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 mtls.mode: STRICT in the namespace
PeerAuthentication defines the authentication policy for workloads within a namespace. Setting `mtls.mode: STRICT` in a PeerAuthentication resource for the 'mesh' namespace enforces that all services in that namespace require mutual TLS for incoming traffic, ensuring that only authenticated and encrypted connections are accepted. This is the correct Istio resource to enforce mTLS at the namespace level.
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.
- ✓
PeerAuthentication with mtls.mode: STRICT in the namespace
Why this is correct
PeerAuthentication with mtls.mode: STRICT enforces mTLS for all services in the namespace.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
VirtualService with tls mode
Why it's wrong here
VirtualService is used for traffic routing, not TLS enforcement.
- ✗
DestinationRule with trafficPolicy.tls.mode: ISTIO_MUTUAL
Why it's wrong here
DestinationRule configures client-side TLS settings, but does not enforce peer authentication across the namespace.
- ✗
ServiceEntry for external services
Why it's wrong here
ServiceEntry is for external services, not internal mTLS enforcement.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The CKS exam often tests the distinction between PeerAuthentication (server-side enforcement) and DestinationRule (client-side configuration), leading candidates to incorrectly choose DestinationRule for namespace-wide mTLS enforcement.
Detailed technical explanation
How to think about this question
PeerAuthentication works at the sidecar proxy level, setting the mTLS mode for inbound traffic to workloads matching the selector (or all workloads in the namespace if no selector is specified). The `STRICT` mode rejects any plaintext HTTP or non-mTLS connections, while `PERMISSIVE` mode allows both. Under the hood, Istio configures Envoy filters to require TLS client certificates and validate them against the mesh CA, ensuring that only workloads with valid SPIFFE identities can communicate. In a real-world scenario, applying a namespace-wide PeerAuthentication with `STRICT` mode is a common step to achieve zero-trust networking within a mesh.
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 mtls.mode: STRICT in the namespace — PeerAuthentication defines the authentication policy for workloads within a namespace. Setting `mtls.mode: STRICT` in a PeerAuthentication resource for the 'mesh' namespace enforces that all services in that namespace require mutual TLS for incoming traffic, ensuring that only authenticated and encrypted connections are accepted. This is the correct Istio resource to enforce mTLS at the namespace level.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more ways this is tested on CKS
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. An administrator wants to enforce mutual TLS (mTLS) between all services in an Istio service mesh. Which resource should be configured?
medium- A.AuthorizationPolicy
- B.ServiceEntry
- C.VirtualService
- ✓ D.PeerAuthentication
Why D: PeerAuthentication is the correct resource because it defines the TLS mode for traffic between services within the Istio mesh. By setting the mode to STRICT, mTLS is enforced, requiring all service-to-service communication to use mutual TLS. This is the Istio-native way to enable mTLS at the mesh or namespace level.
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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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