Azure App Service – Interview Questions

1.1. What is App Service?

Azure App Service is a service for hosting the below type of web applications​

  • App Service – Web App​
  • App Service – API Apps (Web API, WCF etc)​
  • App Service – Mobile back ends.

1.2. What technologies are supported in App Service?

We can develop in our favorite language, be it .NET, .NET Core, Java, Ruby, Node.js, PHP, or Python. ​

1.3. What is the difference between App Service and App Service Plan?

App Service Plan: It’s a managed service that provides the infrastructure (like CPU, RAM etc) for hosting App Services

App Service: It’s a managed service which is used to deploy Web Applications inside the App Service Plan

1.4. What type of applications can be deployed in App Service?

Below type of web applications are supported in App Service

  • App Service – Web App​
  • App Service – API Apps (Web API, WCF etc)​
  • App Service – Mobile back ends.

1.5. Is it possible to create configuration settings in App Service? If yes, what type of configuration settings can be created?

Yes, It’s possible to create the Configuration Setting as Key-Value pairs. App Service supports

  • Application Settings
  • Connection Strings

1.6. In app service. Is it possible to change the runtime stack after the app service is created?

Yes. It’s possible

1.7. What is the significance of always on property in app service?

When Always On is turned on in the configuration, it prevents your app from being idled out due to inactivity

1.8. What is the significance of ARR affinity setting in Azure app service?

ARR affinity – when it’s turned off, the Load Balancer will decides to which server the request should be forwarded. When ARR Affinity is turned on, then the request from a client will always reach the same server for that entire session. For compatibility reasons, ARR Affinity is turned on by default.

1.9. Is it possible to Configure default documents or default page in Azure app service

Yes, It can be done in the Default Documents tab of the Configuration blade of the App Service

1.10. Is it possible to do a remote debugging of applications hosted inside app service

Yes. It’s possible. We need to perform the below steps.

  • Turn on Remote Debugging in the General Settings tab of the Configuration blade of App Service.
  • We also need to deploy the application in Debug mode.

1.11. How do you achieve zero downtime deployment in Azure app service.

In Azure app service. Zero downtime deployment can be achieved using a feature called Deployment Slots.

Deployment slots is available in App Service which is hosted in Standard pricing tier or above.

1.12. Is it really possible to do a blue green deployment in Azure app service

Yes. It is possible to implement blue green deployments in azure app service using the feature called deployment slots

1.13. What is deployment slot of Azure app service? Can you please explain the significance of deployment slots?

Deployment slots are live apps with their own host names. Deploying your application to a non-production slot has the following benefits:

You can validate app changes in a staging deployment slot before swapping it with the production slot. Deploying an app to a slot first and swapping it into production makes sure that all instances of the slot are warmed up before being swapped into production. This eliminates downtime when you deploy your app.

1.14. How do you ensure that the connection strings of database are different for different environments within Azure app service

For all Application Settings and Connection Strings, there is a special attribute setting called Deployment Slot Setting . If you turn this on, then that particular App Setting will become specific to that deployment slot.

1.15. Are there any limitations or challenges that you have faced with Deployment slots in App Service?

As all the Deployment slots (including the Production Slots) share the same infrastructure provdied by the App Service Plan, it is not recommended to perform load testing on staging slots.


1.16. What are the different types of IP addresses that are available with Azure app service.

App service supports 2 types of IP addresses.

  1. Inbound IP address – It is used to configure A record for DNS configuration.
  2. Outbound IP addresses – App Service has multiple Outbound IP Addresses. These are used when app service makes external calls to any other service like databases, web APIs etc. In case if your SQL Database only allows access from IP addresses that are whitelisting in SQL Server, then we need to white list all the outbound IP addresses of app service.

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