You have an on-premises server that runs Windows Server and has the Web Server (IIS) server role installed. The server hosts a web app that connects…

Azure App Service Hybrid Connections provide a secure and direct way for an Azure web app to access on-premises resources, such as a Microsoft SQL Server database. This feature establishes a TCP tunnel from the App Service to a specific on-premises host and port combination. It is configured within the App Service's networking settings and requires installing a small agent, the Hybrid Connection Manager, on the on-premises network. This approach is ideal for this scenario as it doesn't require complex network configurations like a VPN or ExpressRoute, providing a targeted connection from the PaaS application to the on-premises database.

A. an Azure SQL managed instance: This is a fully managed PaaS database service in Azure. The requirement is to connect to the existing on-premises database, not migrate it.

B. an on-premises data gateway: This is primarily used by services like Power BI, Power Automate, and Logic Apps to connect to on-premises data sources, not as the primary connectivity method for App Service web apps.

C. Azure Extended Network: This feature is designed to stretch an on-premises network to Azure, allowing virtual machines to be migrated to Azure while retaining their original IP addresses. It is not for PaaS connectivity.

1. Microsoft Learn

"Azure App Service Hybrid Connections": Under the "How it works" section

it states

"Hybrid Connections can connect App Service apps to on-premises resources that use a static TCP port

such as SQL Server

MySQL

HTTP Web APIs

and most custom web services." This directly validates the use of Hybrid Connections for connecting to an on-premises SQL Server.

2. Microsoft Learn

"App Service networking features": In the comparison table under the "Hybrid Connections" section

the use case is described as "Access resources in other networks." This confirms it as the appropriate feature for connecting from the Azure App Service to an on-premises network.

3. Microsoft Learn

"What is an on-premises data gateway?": This document lists the supported cloud services that use the gateway

including "Power BI

Power Apps

Power Automate

Azure Analysis Services

and Azure Logic Apps." Azure App Service is not listed as a primary consumer

making this option less suitable than the purpose-built Hybrid Connection feature.

4. Microsoft Learn

"Azure Extended Network overview": The overview clearly states

"Azure Extended Network enables you to stretch your on-premises network to Azure for migrating on-premises workloads to Azure while preserving their IP addresses." This confirms its purpose is for IaaS migration

not PaaS-to-on-premises connectivity.