This AZ-900 practice question tests your understanding of describe cloud concepts. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 startup wants to deploy a web application that experiences unpredictable traffic spikes. They need to scale resources automatically without manual intervention. Which benefit of cloud computing directly addresses this requirement?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Elasticity
Elasticity is the cloud computing benefit that enables resources to automatically scale out (add instances) during traffic spikes and scale in (remove instances) when demand drops, without manual intervention. This directly matches the startup's need to handle unpredictable traffic patterns by dynamically adjusting compute capacity, typically using services like Azure Virtual Machine Scale Sets or Azure App Service auto-scale rules.
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.
✗
High availability
Why it's wrong here
High availability ensures that services remain accessible during failures, but it does not inherently provide automatic scaling.
✓
Elasticity
Why this is correct
Elasticity enables automatic scaling of resources to match varying demand, making it the correct choice.
Related concept
Read the scenario before looking for a memorised answer.
✗
Disaster recovery
Why it's wrong here
Disaster recovery focuses on recovering from catastrophic failures, not on scaling resources dynamically.
✗
Fault tolerance
Why it's wrong here
Fault tolerance allows a system to continue operating after component failures, but it does not automatically adjust capacity.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse elasticity with high availability or fault tolerance, because both involve multiple resources, but elasticity specifically addresses dynamic scaling to meet variable demand, not redundancy or failure recovery.
Detailed technical explanation
How to think about this question
Under the hood, elasticity relies on monitoring metrics (e.g., CPU usage, queue depth, or request count) that trigger Azure Autoscale to adjust the instance count via ARM API calls. A subtle behavior is the 'cool-down' period (default 5 minutes) that prevents flapping—rapid scaling actions that could cause instability. In a real-world scenario, a retail app might scale from 2 to 50 VMs during a flash sale, then scale back down, paying only for the extra capacity used.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this AZ-900 question in full detail.
Describe cloud concepts — This question tests Describe cloud concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Elasticity — Elasticity is the cloud computing benefit that enables resources to automatically scale out (add instances) during traffic spikes and scale in (remove instances) when demand drops, without manual intervention. This directly matches the startup's need to handle unpredictable traffic patterns by dynamically adjusting compute capacity, typically using services like Azure Virtual Machine Scale Sets or Azure App Service auto-scale rules.
What should I do if I get this AZ-900 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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