EX280 Networking And Network Policies Practice Question
An administrator observes that pods in a specific namespace are unable to resolve external domain names (e.g., www.redhat.com) while internal service resolution works perfectly. What is the most likely cause of this issue in CoreDNS configuration?
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
✓
The Corefile in the cluster DNS operator configuration has incorrect or missing forward plugins for external resolvers.
CoreDNS forwards external queries to upstream forwarders (like corporate DNS or public resolvers). If the forwarding block in the Corefile is misconfigured, external resolution fails.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The API server service is missing endpoint IPs.
Why it's wrong here
API server endpoints affect management operations, not pod external DNS lookups.
- ✗
NodePort range exhaustion prevents external DNS packets from traversing worker nodes.
Why it's wrong here
DNS traffic does not use NodePorts.
- ✗
The cluster ingress controller is blocking external UDP port 53.
Why it's wrong here
Ingress controllers handle HTTP/TLS traffic, not UDP DNS forwarding.
- ✓
The Corefile in the cluster DNS operator configuration has incorrect or missing forward plugins for external resolvers.
Why this is correct
External resolution depends on CoreDNS forwarding; if forwarders are misconfigured, external lookups fail.
Visual reference
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official Red Hat exam blueprint
This EX280 practice question is part of Courseiva's free Red Hat 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 EX280 exam.