Desired State Configuration (DSC) basics in PowerShell - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this DSC configuration block?

Given the following DSC configuration, what will be the output when you run Start-DscConfiguration -Path .\MyConfig -Wait -Verbose?

PowerShell

Configuration MyConfig {
    Node localhost {
        File ExampleFile {
            DestinationPath = "C:\\Temp\\example.txt"
            Contents = "Hello DSC"
            Ensure = "Present"
        }
    }
}

MyConfig
Start-DscConfiguration -Path .\MyConfig -Wait -Verbose

A The file is created but empty because Contents is ignored.

B An error occurs because the DestinationPath is invalid.

C The file C:\Temp\example.txt is created with content 'Hello DSC'.

D Nothing happens because the configuration is not applied.

💡 Hint

Think about what the File resource does in DSC and what the Ensure property means.

The File resource in DSC creates or ensures the presence of a file at the specified DestinationPath with the given Contents. Running Start-DscConfiguration applies the configuration, so the file will be created with 'Hello DSC'.

📝 Syntax

intermediate

Identify the syntax error in this DSC configuration snippet

Which option correctly fixes the syntax error in this DSC configuration snippet?

PowerShell

Configuration SampleConfig {
    Node localhost {
        File SampleFile {
            DestinationPath = "C:\\Temp\\sample.txt"
            Contents "Sample content"
            Ensure = "Present"
        }
    }
}

A Add an equals sign after Contents: Contents = "Sample content"

B Remove the quotes around Sample content: Contents = Sample content

C Add a comma after Contents: Contents = "Sample content",

D Change DestinationPath to Destination = "C:\\Temp\\sample.txt"

💡 Hint

Look carefully at the property assignments inside the resource block.

In DSC configuration syntax, properties must be assigned with an equals sign. The line 'Contents "Sample content"' is missing the equals sign, causing a syntax error.

🔧 Debug

advanced

Why does this DSC configuration fail to apply?

This DSC configuration is supposed to create a directory, but it fails. What is the reason?

PowerShell

Configuration CreateFolder {
    Node localhost {
        File NewFolder {
            DestinationPath = "C:\\NewFolder"
            Type = "Directory"
            Ensure = "Present"
        }
    }
}

CreateFolder
Start-DscConfiguration -Path .\CreateFolder -Wait -Verbose

A The Node name 'localhost' is invalid and should be replaced with the actual computer name.

B The DestinationPath is missing a trailing backslash.

C The Ensure property must be set to 'Created' instead of 'Present'.

D The 'Type' property is invalid; it should be 'Type = 'Directory'' is correct, but the File resource does not support 'Type'.

💡 Hint

Check the documentation for the File resource properties.

The File resource in DSC requires the DestinationPath to end with a trailing backslash when Type = 'Directory'. Without it, the configuration fails to apply.

🚀 Application

advanced

How to ensure a Windows feature is installed using DSC?

You want to use DSC to make sure the 'Web-Server' Windows feature is installed on a server. Which configuration snippet will achieve this?

A

Configuration WebServer {
    Node localhost {
        WindowsFeature IIS {
            Name = "Web-Server"
            Ensure = "Present"
        }
    }
}

B

Configuration WebServer {
    Node localhost {
        WindowsFeature IIS {
            FeatureName = "Web-Server"
            State = "Installed"
        }
    }
}

C

Configuration WebServer {
    Node localhost {
        WindowsFeature IIS {
            Name = "Web-Server"
            State = "Present"
        }
    }
}

D

Configuration WebServer {
    Node localhost {
        WindowsFeature IIS {
            FeatureName = "Web-Server"
            Ensure = "Installed"
        }
    }
}

💡 Hint

Check the correct property names and values for the WindowsFeature resource.

The WindowsFeature resource uses 'Name' to specify the feature and 'Ensure' with values 'Present' or 'Absent' to install or remove the feature. 'FeatureName' and 'State' are invalid properties.

🧠 Conceptual

expert

What happens if you run Start-DscConfiguration twice with the same configuration?

You have applied a DSC configuration named 'MyConfig' on a node. You run Start-DscConfiguration -Path .\MyConfig -Wait -Verbose again immediately. What will happen?

A DSC will uninstall all resources and then apply the configuration again.

B DSC will reapply the configuration and recreate all resources regardless of current state.

C DSC will throw an error because the configuration is already applied.

D DSC will detect the node is already in the desired state and make no changes.

💡 Hint

Think about the purpose of DSC's idempotency.

DSC is designed to be idempotent. Running the same configuration again checks the current state and only makes changes if needed. If the node is already compliant, no changes occur.