AZ-900 Describe Azure architecture and services Practice Question
A developer is building a serverless application that requires integration with an on-premises SQL Server database for real-time data processing. The on-premises network is connected to Azure via a site-to-site VPN. Which Azure service would allow the function to securely access the on-premises database without exposing it to the public internet?
⚠ Common exam trap
Test-takers frequently assume Azure Functions in any plan can access on-premises resources via VPN, but only the Premium and Dedicated plans support VNet integration, while the Consumption plan is restricted to public endpoints.
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
✓
Azure Functions in Premium plan with VNet integration
Azure Functions in the Premium plan supports VNet integration, allowing the function to securely access resources in a connected on-premises network via a site-to-site VPN without exposing the database to the public internet. The Consumption plan lacks VNet integration, and Azure SQL Database is a PaaS service, not a compute service for running serverless code.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Azure Functions in Consumption plan
Why it's wrong here
The Consumption plan runs serverless functions in a shared, multi-tenant environment with dynamic scaling but without the ability to integrate with a virtual network. A function app on the Consumption plan cannot join a VNet, so it cannot use VPN gateways or ExpressRoute to reach on-premises resources. Only the Premium or Dedicated plans offer VNet integration, making the Consumption plan unsuitable for this private connectivity requirement.
When this WOULD be correct
A question where the requirement is to run code in response to events with automatic scaling and pay-per-execution pricing, and there is no need for VNet access or integration with on-premises resources.
- ✓
Azure Functions in Premium plan with VNet integration
Why this is correct
Azure Functions Premium plan supports VNet integration, enabling your function app to route outbound and inbound calls to and from resources in a virtual network. With a site-to-site VPN or ExpressRoute, you can securely connect that VNet to your on-premises SQL Server, keeping database traffic off the public internet. This preserves the event-driven serverless model while providing private, predictable network access.
- ✗
Azure SQL Database
Why it's wrong here
Azure SQL Database is a fully managed cloud database service, not a network connectivity option. The requirement is to keep and access an existing on-premises SQL Server, so adopting Azure SQL Database would necessitate a migration and re-architecture, which is out of scope. It does not establish any private communication path from Azure Functions to the on-premises SQL instance.
When this WOULD be correct
A question asks: 'Which Azure service provides a fully managed relational database with built-in high availability and automatic backups, without needing to manage the underlying infrastructure?' In that scenario, Azure SQL Database would be the correct answer.
- ✗
Hybrid Connections
Why it's wrong here
Hybrid Connections is a relay-based connectivity feature that uses the Hybrid Connection Manager agent installed on-premises to open an outbound connection to Azure. It is primarily exposed through Azure App Service, not natively as an Azure Functions feature, and the relay topology adds agent dependencies and latency. For a serverless function app needing direct, secure on-premises SQL access, VNet integration is a more appropriate architectural fit.
When this WOULD be correct
A question where an Azure App Service or Azure Function needs to access an on-premises resource that is not connected via VPN or ExpressRoute, and the on-premises network cannot be directly routed. For example: 'You need to allow an Azure web app to connect to an on-premises SQL Server database without opening firewall ports. The on-premises network has no VPN to Azure.'
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.
✓Azure Functions in Premium plan with VNet integrationCorrect answer▾
Why this is correct
Azure Functions Premium plan supports VNet integration, enabling your function app to route outbound and inbound calls to and from resources in a virtual network. With a site-to-site VPN or ExpressRoute, you can securely connect that VNet to your on-premises SQL Server, keeping database traffic off the public internet. This preserves the event-driven serverless model while providing private, predictable network access.
✗Azure Functions in Consumption planWrong answer — click to see why▾
Why this is wrong here
Azure Functions in Consumption plan cannot use VNet integration, so they cannot securely access on-premises resources via a site-to-site VPN without exposing them to the public internet.
★ When this WOULD be the correct answer
A question where the requirement is to run code in response to events with automatic scaling and pay-per-execution pricing, and there is no need for VNet access or integration with on-premises resources.
Why candidates choose this
Candidates may think all Azure Functions plans support VNet integration, or they focus on the 'serverless' aspect without considering the connectivity requirements.
✗Azure SQL DatabaseWrong answer — click to see why▾
Why this is wrong here
Azure SQL Database is a cloud-based PaaS offering, not an on-premises SQL Server. The question requires integration with an on-premises database, so Azure SQL Database does not address the need to access the existing on-premises SQL Server.
★ When this WOULD be the correct answer
A question asks: 'Which Azure service provides a fully managed relational database with built-in high availability and automatic backups, without needing to manage the underlying infrastructure?' In that scenario, Azure SQL Database would be the correct answer.
Why candidates choose this
Candidates may confuse Azure SQL Database with a way to connect to on-premises SQL Server, or they might think it can be used as a proxy, but it is a separate cloud database, not a connectivity service.
✗Hybrid ConnectionsWrong answer — click to see why▾
Why this is wrong here
Hybrid Connections is designed for outbound connections from Azure to on-premises resources, but it requires a relay agent and does not support VNet integration for secure, private access. The question specifies a site-to-site VPN, which aligns with VNet integration for direct, secure access without exposing the database to the public internet.
★ When this WOULD be the correct answer
A question where an Azure App Service or Azure Function needs to access an on-premises resource that is not connected via VPN or ExpressRoute, and the on-premises network cannot be directly routed. For example: 'You need to allow an Azure web app to connect to an on-premises SQL Server database without opening firewall ports. The on-premises network has no VPN to Azure.'
Why candidates choose this
Hybrid Connections sounds like it would securely connect Azure to on-premises, and candidates may confuse it with VNet integration or assume it works with site-to-site VPNs, not realizing it uses a different mechanism (relay) that is less suitable for real-time, high-throughput scenarios.
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
Serverless
Serverless is a cloud computing model where the cloud provider manages the servers, and you only pay for the actual compute time your code uses, without having to worry about provisioning or maintaining infrastructure.
Key term
PaaS
Platform as a Service (PaaS) is a cloud computing model that provides a managed platform for developers to build, run, and manage applications without dealing with the underlying infrastructure.
About these practice questions
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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.