- A
Use the Kubernetes DNS service to resolve the Service name 'service-b'
Kubernetes DNS automatically creates DNS records for Services, making this the standard approach for service discovery.
- B
Use an external service registry like Consul or etcd
Why wrong: While possible, this is not the most Kubernetes-native approach; Kubernetes provides built-in service discovery via DNS.
- C
Hardcode the cluster IP of Service B in the configuration of Service A
Why wrong: Hardcoding is brittle and does not adapt to changes in the Service's IP.
- D
Use environment variables injected by the Kubernetes API into each pod
Why wrong: While environment variables are injected, they are not updated if the Service changes, and they are less flexible than DNS-based discovery.
Question 945 of 997
Kubernetes Service Discovery: DNS Over Environment Variables
This KCNA practice question tests your understanding of container orchestration. 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 a microservices application where Service A needs to discover the IP of Service B. Both services run in the same Kubernetes cluster. Which approach is the most Kubernetes-native way for Service A to reach Service B?
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
✓
Use the Kubernetes DNS service to resolve the Service name 'service-b'
Kubernetes has a built-in DNS service (typically CoreDNS) that automatically creates DNS records for Services. When Service A resolves the name 'service-b' (or 'service-b.<namespace>.svc.cluster.local'), the DNS returns the cluster IP of Service B's Service object, which then load-balances traffic to the healthy Pods. This is the most Kubernetes-native approach because it leverages the platform's own service discovery mechanism without external dependencies.
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.
- ✓
Use the Kubernetes DNS service to resolve the Service name 'service-b'
Why this is correct
Kubernetes DNS automatically creates DNS records for Services, making this the standard approach for service discovery.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use an external service registry like Consul or etcd
Why it's wrong here
While possible, this is not the most Kubernetes-native approach; Kubernetes provides built-in service discovery via DNS.
- ✗
Hardcode the cluster IP of Service B in the configuration of Service A
Why it's wrong here
Hardcoding is brittle and does not adapt to changes in the Service's IP.
- ✗
Use environment variables injected by the Kubernetes API into each pod
Why it's wrong here
While environment variables are injected, they are not updated if the Service changes, and they are less flexible than DNS-based discovery.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think environment variables (Option D) are the primary Kubernetes-native method, but the exam emphasizes DNS as the modern, recommended approach, while environment variables are a legacy fallback with limitations.
Detailed technical explanation
How to think about this question
Under the hood, CoreDNS watches the Kubernetes API for Service and EndpointSlice objects, automatically updating DNS A/AAAA records. The default search domain includes <service>.<namespace>.svc.cluster.local, so a simple 'service-b' resolves within the same namespace. A real-world scenario: if Service B is in a different namespace, the full FQDN 'service-b.other-ns.svc.cluster.local' must be used, which is a common source of misconfiguration.
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 KCNA 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.
Visual reference
Quick reference
Common DNS Record Types
| Record | Purpose | Example |
|---|---|---|
| A | IPv4 address mapping | example.com → 93.184.216.34 |
| AAAA | IPv6 address mapping | example.com → 2606:2800::1 |
| CNAME | Alias to another hostname | www → example.com |
| MX | Mail server for domain | example.com → mail.example.com (priority 10) |
| TXT | Text data (SPF, DKIM, verification) | v=spf1 include:_spf.example.com ~all |
| NS | Authoritative name servers | example.com NS ns1.example.com |
| PTR | Reverse DNS (IP → hostname) | 34.216.184.93.in-addr.arpa → example.com |
| SOA | Zone authority record | Primary NS, admin email, serial, TTL defaults |
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.
- →
Container Orchestration — study guide chapter
Learn the concepts, then practise the questions
- →
Container Orchestration practice questions
Targeted practice on this topic area only
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FAQ
Questions learners often ask
What does this KCNA question test?
Container Orchestration — This question tests Container Orchestration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use the Kubernetes DNS service to resolve the Service name 'service-b' — Kubernetes has a built-in DNS service (typically CoreDNS) that automatically creates DNS records for Services. When Service A resolves the name 'service-b' (or 'service-b.<namespace>.svc.cluster.local'), the DNS returns the cluster IP of Service B's Service object, which then load-balances traffic to the healthy Pods. This is the most Kubernetes-native approach because it leverages the platform's own service discovery mechanism without external dependencies.
What should I do if I get this KCNA 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
2 more ways this is tested on KCNA
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. You are designing a microservices application that requires each service to be independently deployable and scalable. The services communicate over HTTP and need service discovery. Which orchestration feature BEST addresses the need for service discovery?
medium- ✓ A.Kubernetes Service
- B.Horizontal Pod Autoscaler
- C.ConfigMap
- D.PersistentVolume
Why A: Kubernetes Service is the correct choice because it provides a stable network endpoint (IP address and DNS name) for a set of pods, enabling service discovery via DNS or environment variables. This allows microservices to locate and communicate with each other over HTTP without hardcoding IP addresses, which is essential for independent deployability and scalability.
Variation 2. A microservices application has multiple services that need to discover each other by name. Which Kubernetes object provides built-in service discovery via DNS?
hard- A.Ingress
- B.Namespace
- C.ConfigMap
- ✓ D.Service
Why D: Option D is correct because a Kubernetes Service object provides built-in service discovery via DNS. When a Service is created, the cluster's DNS (typically CoreDNS) automatically assigns it a DNS name in the format `<service>.<namespace>.svc.cluster.local`, allowing other microservices to resolve the Service by name without hardcoding IP addresses or using external service registries.
Keep practising
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Last reviewed: Jun 24, 2026
This KCNA 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 KCNA exam.
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