- A
Elasticity
Why wrong: Elasticity refers to the ability to automatically provision and de-provision resources to match demand. The scenario does not involve scaling up or down based on load; it is about surviving a failure. Therefore, elasticity is not the correct concept.
- B
Fault tolerance
Fault tolerance is the correct concept. The Multi-AZ RDS configuration allows the database to automatically fail over to a standby instance in a different Availability Zone when the primary fails. This ensures continuous operation despite a component failure, which is the definition of fault tolerance.
- C
Scalability
Why wrong: Scalability is the ability to increase or decrease resources to handle varying workloads. While Auto Scaling would demonstrate scalability, this scenario does not involve changing the amount of resources; it is about ensuring availability during a failure. Thus, scalability is not the best answer.
- D
Resource pooling
Why wrong: Resource pooling is a characteristic of cloud computing where the provider's computing resources are pooled to serve multiple customers using a multi-tenant model. The scenario is about database redundancy across AZs, not about sharing resources among customers. Therefore, resource pooling is incorrect.
CLF-C02 Cloud Concepts Practice Question
This CLF-C02 practice question tests your understanding of cloud concepts. 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.
A company runs a customer-facing web application with an Amazon RDS database. Initially, the database is deployed as a single instance in one Availability Zone (AZ). A power outage occurs in that AZ, causing the database to become unavailable for several hours. After the incident, the company modifies the database to use a Multi-AZ configuration. Shortly after the change, another power outage affects the same primary AZ. This time, the database automatically fails over to the standby instance in the other AZ without any manual intervention, and the application remains available. Which cloud computing concept does this scenario best demonstrate?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"best"Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Clue:
"primary"Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
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
Fault tolerance
Fault tolerance is the ability of a system to continue operating without interruption when one or more of its components fail. In this scenario, the Multi-AZ RDS deployment automatically failed over to a standby instance in a different Availability Zone when the primary AZ experienced a power outage, ensuring the application remained available without manual intervention. This demonstrates fault tolerance because the system was designed to withstand the failure of an entire AZ and continue functioning.
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.
- ✗
Elasticity
Why it's wrong here
Elasticity refers to the ability to automatically provision and de-provision resources to match demand. The scenario does not involve scaling up or down based on load; it is about surviving a failure. Therefore, elasticity is not the correct concept.
- ✓
Fault tolerance
Why this is correct
Fault tolerance is the correct concept. The Multi-AZ RDS configuration allows the database to automatically fail over to a standby instance in a different Availability Zone when the primary fails. This ensures continuous operation despite a component failure, which is the definition of fault tolerance.
Clue confirmation
The clue words "best", "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Scalability
Why it's wrong here
Scalability is the ability to increase or decrease resources to handle varying workloads. While Auto Scaling would demonstrate scalability, this scenario does not involve changing the amount of resources; it is about ensuring availability during a failure. Thus, scalability is not the best answer.
- ✗
Resource pooling
Why it's wrong here
Resource pooling is a characteristic of cloud computing where the provider's computing resources are pooled to serve multiple customers using a multi-tenant model. The scenario is about database redundancy across AZs, not about sharing resources among customers. Therefore, resource pooling is incorrect.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse fault tolerance with high availability or elasticity, but fault tolerance specifically implies zero downtime during a failure, whereas high availability may involve a brief interruption, and elasticity is about scaling, not failure recovery.
Trap categories for this question
Scenario analysis trap
Elasticity refers to the ability to automatically provision and de-provision resources to match demand. The scenario does not involve scaling up or down based on load; it is about surviving a failure. Therefore, elasticity is not the correct concept.
Detailed technical explanation
How to think about this question
Amazon RDS Multi-AZ uses synchronous replication to the standby instance in a different AZ, ensuring zero data loss during failover. The failover is automatically triggered by Amazon's DNS and health-check mechanisms, typically completing within 60-120 seconds. In a real-world scenario, this design protects against not only AZ power outages but also instance failures, network disruptions, and planned maintenance events.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
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.
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FAQ
Questions learners often ask
What does this CLF-C02 question test?
Cloud Concepts — This question tests Cloud Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Fault tolerance — Fault tolerance is the ability of a system to continue operating without interruption when one or more of its components fail. In this scenario, the Multi-AZ RDS deployment automatically failed over to a standby instance in a different Availability Zone when the primary AZ experienced a power outage, ensuring the application remained available without manual intervention. This demonstrates fault tolerance because the system was designed to withstand the failure of an entire AZ and continue functioning.
What should I do if I get this CLF-C02 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: "best", "primary". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This CLF-C02 practice question is part of Courseiva's free Amazon Web Services 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 CLF-C02 exam.
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