EX280 Networking And Network Policies Practice Question
An administrator creates a NetworkPolicy that restricts egress traffic from a namespace. However, DNS resolution for external services immediately stops working. What is the cause of this behavior?
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 NetworkPolicy blocks outbound traffic to port 53 on the cluster DNS service.
Pods rely on CoreDNS services for name resolution. If egress rules are applied without explicitly allowing UDP/TCP traffic to port 53 on the cluster DNS service or cluster CIDR, DNS queries are blocked.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
NetworkPolicies automatically disable the OpenShift SDN controller.
Why it's wrong here
NetworkPolicies do not disable the SDN controller.
- ✓
The NetworkPolicy blocks outbound traffic to port 53 on the cluster DNS service.
Why this is correct
Restricting egress blocks DNS queries sent to CoreDNS unless specifically allowed.
- ✗
CoreDNS pods do not have valid security context constraints.
Why it's wrong here
SCCs do not cause DNS lookup failures following a NetworkPolicy application.
- ✗
External DNS servers reject requests originating from OpenShift node IPs.
Why it's wrong here
Internal cluster DNS is handled by CoreDNS within the cluster, not external servers directly.
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.