- A
A PeerAuthentication resource with mTLS mode set to STRICT and a namespace selector
PeerAuthentication with mtls.mode: STRICT enforces mTLS for the selected namespace or workloads.
- B
A DestinationRule resource with trafficPolicy tls mode set to ISTIO_MUTUAL
Why wrong: DestinationRule configures client-side TLS settings, but PeerAuthentication is the primary resource for enforcing mTLS for the namespace.
- C
A VirtualService with a rewrite rule to enforce TLS
Why wrong: VirtualService handles traffic routing, not mTLS enforcement.
- D
A ServiceEntry to define external services
Why wrong: ServiceEntry is for external services, not for internal mTLS enforcement.
Question 391 of 997
Istio PeerAuthentication for mTLS Enforcement in a Namespace
This CKS practice question tests your understanding of minimize microservice vulnerabilities. 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.
You have deployed a service mesh with Istio and want to enforce mutual TLS (mTLS) for all traffic between services in the 'mesh' namespace. Which resource should you create?
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
✓
A PeerAuthentication resource with mTLS mode set to STRICT and a namespace selector
A PeerAuthentication resource with mTLS mode set to STRICT and a namespace selector enforces mutual TLS for all traffic within the specified namespace. This is the correct Istio resource to define mTLS policies at the namespace level, as it applies to all workloads in the namespace without requiring individual DestinationRules.
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.
- ✓
A PeerAuthentication resource with mTLS mode set to STRICT and a namespace selector
Why this is correct
PeerAuthentication with mtls.mode: STRICT enforces mTLS for the selected namespace or workloads.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
A DestinationRule resource with trafficPolicy tls mode set to ISTIO_MUTUAL
Why it's wrong here
DestinationRule configures client-side TLS settings, but PeerAuthentication is the primary resource for enforcing mTLS for the namespace.
- ✗
A VirtualService with a rewrite rule to enforce TLS
Why it's wrong here
VirtualService handles traffic routing, not mTLS enforcement.
- ✗
A ServiceEntry to define external services
Why it's wrong here
ServiceEntry is for external services, not for internal mTLS enforcement.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap is confusing PeerAuthentication (which enforces mTLS on the server side) with DestinationRule (which only configures client-side TLS settings). Candidates may incorrectly select a DestinationRule for namespace-wide mTLS enforcement, but only PeerAuthentication with STRICT mode enforces mTLS at the namespace level. This is a common trap in CNCF exams.
Detailed technical explanation
How to think about this question
PeerAuthentication uses the mTLS mode field (DISABLE, PERMISSIVE, or STRICT) to control whether workloads accept plaintext or mTLS connections. When set to STRICT, the sidecar proxy rejects any non-mTLS traffic, enforcing mutual TLS at the transport layer. This is part of Istio's security model, which leverages Envoy proxies to handle TLS termination and certificate validation automatically.
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.
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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: A PeerAuthentication resource with mTLS mode set to STRICT and a namespace selector — A PeerAuthentication resource with mTLS mode set to STRICT and a namespace selector enforces mutual TLS for all traffic within the specified namespace. This is the correct Istio resource to define mTLS policies at the namespace level, as it applies to all workloads in the namespace without requiring individual DestinationRules.
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. In the context of service mesh (e.g., Istio), which resource is used to enforce mutual TLS (mTLS) between services in a specific namespace?
easy- ✓ A.PeerAuthentication
- B.VirtualService
- C.DestinationRule
- D.ServiceEntry
Why A: PeerAuthentication is the correct resource because it defines the mutual TLS (mTLS) mode for workloads within a namespace or mesh. In Istio, PeerAuthentication allows you to enforce STRICT mTLS, which requires all traffic between services in the specified namespace to use TLS certificates for both client and server authentication, preventing plaintext or unauthenticated communication.
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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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