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CV0-004 Practice Question: Uses a cloud-based load balancer to distribute…
An organization uses a cloud-based load balancer to distribute traffic to a web application across multiple availability zones. Users report that the application is intermittently unavailable. The cloud administrator finds that the load balancer health checks are failing on instances in one availability zone. What is the most likely cause?
⚠ Common exam trap
CompTIA often tests the distinction between instance-level failures and zone-level failures; the trap here is that candidates may assume a single misconfigured instance (Option B) is the cause, but the key clue is that all instances in one AZ are failing health checks, which points to an AZ-wide issue rather than a per-instance configuration problem.
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 availability zone is experiencing a partial outage.
When health checks fail for all instances in a single availability zone (AZ) while other AZs remain healthy, the most likely cause is a partial outage or degradation within that AZ. Cloud providers like AWS, Azure, or GCP isolate AZs to prevent single points of failure, but an AZ can experience issues such as network connectivity loss, power disruption, or hardware failures that affect all instances in that zone. The load balancer's health checks are designed to detect such zone-level failures by probing each instance; if an entire AZ is impaired, all its instances will fail the health check simultaneously.
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 availability zone is experiencing a partial outage.
Why this is correct
AZ outage would cause all instances to fail health checks.
- ✗
A single instance in the failing AZ has a misconfigured web server.
Why it's wrong here
Would affect only that instance, not all in AZ.
- ✗
The DNS settings for the application domain are misconfigured.
Why it's wrong here
DNS does not cause health check failures.
- ✗
The load balancer's listener configuration is incorrect.
Why it's wrong here
Would affect all AZs equally.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CV0-004 practice question is part of Courseiva's free CompTIA 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 CV0-004 exam.