A financial services company runs a high-frequency stock trading platform on AWS. The platform must continue processing trades without any interruption, even if an entire AWS Availability Zone experiences a complete outage. The architecture is designed with duplicate infrastructure in multiple Availability Zones, and all components are active simultaneously. The system is engineered so that if one AZ fails, the remaining AZs continue processing trades instantly, with zero downtime for end users. Which cloud computing concept does this requirement BEST represent?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
Distractor review
Elasticity
Elasticity refers to the ability to automatically scale computing resources up or down based on demand. While the platform may also be elastic, the core requirement described is about surviving a failure with zero interruption, not about scaling.
Distractor review
High availability
High availability typically involves redundant components and automatic failover, but it generally allows for a short period of downtime (seconds or minutes) during the failover process. The scenario explicitly states 'zero downtime,' which is a more stringent requirement that aligns with fault tolerance.
Best answer
Fault tolerance
Fault tolerance is the property that enables a system to continue functioning correctly even when some of its components fail. The scenario's demand for 'zero downtime' and 'instant' continuation of processing after an AZ failure directly matches the definition of fault tolerance. This is typically achieved through active-active redundant deployments.
Distractor review
Durability
Durability refers to the long-term protection of data from loss or corruption, often associated with storage services like Amazon S3 (e.g., 99.999999999% durability). It is not related to application uptime or continued processing during an infrastructure failure.
Common exam trap
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Technical deep dive
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A developer needs to launch a test server for a new application prototype. The developer logs into the AWS Management Console, selects an Amazon EC2 instance type, configures the security group, and starts the instance. The instance is running within two minutes, and the developer did not need to submit a formal request to the company's IT procurement team or wait for approval from a cloud administrator. Which essential characteristic of cloud computing does this scenario best demonstrate?
Question 2
A solutions architect is planning a new web application on AWS. The workload will include 3 Amazon EC2 instances (t3.medium) running 24/7, an Application Load Balancer, and an Amazon RDS for MySQL db.t3.small database. The architect needs to estimate the monthly cost for the first year, considering different purchasing options (On-Demand, 1-year All Upfront Reserved Instance, and Compute Savings Plan). Which AWS tool should the architect use to create this estimate?
Question 3
A company's development team frequently needs temporary test environments. A developer can log into the AWS Management Console, select an Amazon EC2 instance type, configure storage, and launch the instance within minutes without any interaction with the IT infrastructure team. This capability is an example of which essential characteristic of cloud computing?
Question 4
A company's finance team needs to analyze AWS spending in detail. They require a report that includes hourly cost data for each AWS service, each individual resource (e.g., a specific EC2 instance), and any cost allocation tags applied. The team plans to export this data to an Amazon S3 bucket and then import it into a custom business intelligence (BI) analytics dashboard. Which AWS tool should the finance team use to generate this level of detailed cost data?
Question 5
A company uses AWS for its development environment. The finance team wants to set a monthly budget of $10,000. They want to receive an email notification when the actual costs reach 80% of the budget ($8,000) and again when costs exceed the budget. The team needs a managed AWS service that can automatically send these alerts without requiring custom code or third-party tools. Which AWS service should the team use?
Question 6
A company uses AWS Organizations to manage multiple accounts. The security team needs to enforce a policy that restricts SSH access (port 22) from the internet (0.0.0.0/0) in all VPCs across all accounts. The team wants to centrally define the allowed rules and automatically apply them to newly created VPCs and security groups, while also automatically remediating any existing non-compliant security groups. Which AWS service should the team use?
FAQ
Questions learners often ask
What does this CLF-C02 question test?
Read the scenario before looking for a memorised answer.
What is the correct answer to this question?
The correct answer is: Fault tolerance — The scenario requires zero downtime in the event of an Availability Zone failure. This is the defining characteristic of fault tolerance. Fault tolerance ensures a system continues to operate without interruption despite component failures, typically through active-active redundant components. High availability (HA) also uses redundancy but often allows for a brief period of downtime during failover. Elasticity focuses on scaling resources based on demand, and durability refers to data persistence over time. Therefore, fault tolerance is the best answer.
What should I do if I get this CLF-C02 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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