You plan to deploy several Azure virtual machines that will run Windows Server 2019 in a virtual machine scale set by using an Azure Resource Manager template. ...

Azure virtual machine extensions are small packages that run post-deployment configuration and automation on Azure virtual machines.
In the following example, the Azure CLI is used to deploy a custom script extension to an existing virtual machine, which installs a Nginx webserver. az vm extension set \
--resource-group myResourceGroup \
--vm-name myVM --name customScript \
--publisher Microsoft.Azure.Extensions \
--settings '{"commandToExecute": "apt-get install -y nginx"}
Note:
There are several versions of this question in the exam. The question has two correct answers:
1. a Desired State Configuration (DSC) extension
2. Azure Custom Script Extension
The question can have other incorrect answer options, including the following:
- the Publish-AzVMDscConfiguration cmdlet
- Azure Application Insights
Reference:
https://docs.microsoft.com/en-us/azure/architecture/framework/devops/automation-configuration