This CV0-004 practice question tests your understanding of operations and support. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
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?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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.
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.
✓
The availability zone is experiencing a partial outage.
Why this is correct
AZ outage would cause all instances to fail health checks.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
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.
The load balancer's listener configuration is incorrect.
Why it's wrong here
Would affect all AZs equally.
Common exam traps
Common exam trap: answer the scenario, not the keyword
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.
Detailed technical explanation
How to think about this question
Cloud load balancers (e.g., AWS ALB, Azure Load Balancer) perform health checks by sending periodic probes (e.g., HTTP GET requests or TCP SYN packets) to each registered instance. If an AZ experiences a network partition or a failure in the underlying hypervisor or physical infrastructure, all instances in that AZ become unreachable, causing the load balancer to mark them as unhealthy and stop routing traffic to them. This behavior is governed by the load balancer's health check interval and threshold settings (e.g., 5-second interval, 2 consecutive failures), and the failover to healthy AZs is automatic, but users may experience intermittent unavailability if the unhealthy AZ handles a significant portion of traffic before health checks detect the failure.
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 CV0-004 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.
Operations and Support — This question tests Operations and Support — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this CV0-004 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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