AZ-900 Describe Azure architecture and services Practice Question
A company uses Azure SQL Database for a web application. They need to ensure that the database can automatically scale to handle sudden spikes in traffic without downtime. Which feature should they enable?
⚠ Common exam trap
Candidates often confuse high-availability features (like geo-replication or elastic pools) with automatic compute scaling, but serverless compute is the only option that directly addresses dynamic scaling of compute resources without downtime for a single Azure SQL Database.
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
✓
Serverless compute
Serverless compute for Azure SQL Database automatically scales compute resources based on workload demand and pauses the database during idle periods, charging only for consumed resources. This enables handling sudden traffic spikes without downtime because the service dynamically adjusts the vCore count and memory within a configurable range, ensuring continuous availability during bursts.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Geo-replication
Why it's wrong here
Geo-replication is a data-availability feature that asynchronously maintains a read-only secondary copy of the database in a different Azure region to support disaster recovery, not workload scaling. It does not react to CPU or memory pressure, so it cannot help a web application that needs more compute capacity during traffic spikes. Its purpose is to fail over or recover from regional outages, not to handle variable application demand.
When this WOULD be correct
A company needs to ensure database availability during a regional outage and wants to failover to a secondary region with minimal data loss. Geo-replication would be correct for disaster recovery.
- ✓
Serverless compute
Why this is correct
Serverless compute in Azure SQL Database automatically scales compute resources based on the workload's active connections, CPU, and memory usage, pausing the database during idle periods to eliminate compute billing. It provides per-second billing and can burst to a configurable maximum vCore, making it ideal for intermittent usage patterns with unpredictable spikes. Because scaling is fully automated, there is no manual adjustment or capacity planning required.
- ✗
Active geo-replication
Why it's wrong here
Active geo-replication builds on geo-replication by creating readable secondary replicas that can serve read-only queries, which offloads read traffic but leaves the primary's compute footprint unchanged. The secondary replicas use their own compute resources, and you must statically size them; they do not scale automatically based on the application's needs. This feature addresses high availability and read throughput, not the automatic compute scaling required for a spiky, intermittent workload.
When this WOULD be correct
Active geo-replication would be correct for a question requiring high availability and disaster recovery across regions, such as: 'A company needs a database solution that supports failover to a secondary region during a regional outage with minimal data loss.'
- ✗
Elastic pool
Why it's wrong here
Elastic pools allocate a shared set of compute and storage resources across multiple Azure SQL databases, allowing individual databases to borrow capacity up to a per-database limit, but the pool's total resources must be resized manually or scheduled. While it provides cost efficiency for mixed workloads, it does not automatically scale the compute tier in response to a single database's spikes. The web application's database would contend with other databases for the same pool resources, and the pool itself requires manual management of its eDTUs or vCores.
When this WOULD be correct
An exam question asking for a cost-effective solution to manage unpredictable usage across multiple databases with varying resource needs, where the goal is to share resources and optimize costs rather than auto-scale a single database.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The AZ-900 exam frequently reuses these exact scenarios with slightly different constraints.
✓Serverless computeCorrect answer▾
Why this is correct
Serverless compute in Azure SQL Database automatically scales compute resources based on the workload's active connections, CPU, and memory usage, pausing the database during idle periods to eliminate compute billing. It provides per-second billing and can burst to a configurable maximum vCore, making it ideal for intermittent usage patterns with unpredictable spikes. Because scaling is fully automated, there is no manual adjustment or capacity planning required.
✗Geo-replicationWrong answer — click to see why▾
Why this is wrong here
Geo-replication provides disaster recovery and read-scale, not automatic scaling for traffic spikes. It replicates data to another region but does not adjust compute resources dynamically.
★ When this WOULD be the correct answer
A company needs to ensure database availability during a regional outage and wants to failover to a secondary region with minimal data loss. Geo-replication would be correct for disaster recovery.
Why candidates choose this
Candidates may confuse geo-replication with scaling because it involves multiple copies of the database, but it does not handle sudden traffic spikes or automatic compute scaling.
✗Active geo-replicationWrong answer — click to see why▾
Why this is wrong here
Active geo-replication provides disaster recovery and read-scale, not automatic scaling for sudden traffic spikes. It requires manual scaling or pre-provisioned resources, so it cannot automatically handle sudden spikes without downtime.
★ When this WOULD be the correct answer
Active geo-replication would be correct for a question requiring high availability and disaster recovery across regions, such as: 'A company needs a database solution that supports failover to a secondary region during a regional outage with minimal data loss.'
Why candidates choose this
Candidates may confuse 'active geo-replication' with automatic scaling because 'active' suggests responsiveness, and they might think replication can distribute load to handle spikes, but it's designed for availability, not elasticity.
✗Elastic poolWrong answer — click to see why▾
Why this is wrong here
Elastic pools provide resource sharing among multiple databases but do not enable automatic scaling of a single database in response to sudden traffic spikes without downtime; they require manual scaling or predefined limits.
★ When this WOULD be the correct answer
An exam question asking for a cost-effective solution to manage unpredictable usage across multiple databases with varying resource needs, where the goal is to share resources and optimize costs rather than auto-scale a single database.
Why candidates choose this
Candidates may confuse elastic pools with auto-scaling because pools allow databases to share resources, but they do not automatically scale a single database on demand.
Analysis generated from the official AZ-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
Go deeper
Related to this question
Learn chapter
Azure Regions and Geographies
Key term
Azure SQL Database
Azure SQL Database is a fully managed relational database-as-a-service (DBaaS) in Microsoft Azure, based on the SQL Server engine, that handles scaling, backups, patching, and high availability automatically.
Key term
Feature
A feature is a distinct unit of functionality that delivers value to the user, often managed and tracked throughout the software development lifecycle.
About these practice questions
This AZ-900 question is part of Courseiva's 981-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This AZ-900 practice question is part of Courseiva's free Microsoft 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 AZ-900 exam.