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.

Practice

1. What is the main purpose of Desired State Configuration (DSC) in PowerShell?

easy

A. To monitor network traffic continuously

B. To write scripts that run only once manually

C. To automatically keep your computer setup as you want it

D. To create user accounts interactively

Solution

1. Step 1: Understand DSC's role

   DSC is designed to keep system configurations consistent automatically.

2. Step 2: Compare options

   Only To automatically keep your computer setup as you want it describes automatic maintenance of computer setup, which is DSC's goal.

3. Final Answer:

   To automatically keep your computer setup as you want it -> Option C

4. Quick Check:

   DSC purpose = automatic setup maintenance [OK]

Hint: DSC means automatic setup enforcement [OK]

Common Mistakes:

• Thinking DSC only runs scripts once
• Confusing DSC with network monitoring
• Assuming DSC manages user accounts interactively

2. Which of the following is the correct way to start a DSC configuration block in PowerShell?

easy

A. Start-DSCConfig MyConfig { }

B. Configuration MyConfig { }

C. Config MyConfig { }

D. New-DSCConfig -Name MyConfig { }

Solution

1. Step 1: Recall DSC syntax

   The DSC configuration block always starts with the keyword 'Configuration' followed by the name.

2. Step 2: Check options

   Only Configuration MyConfig { } uses the correct keyword 'Configuration' to define the block.

3. Final Answer:

   Configuration MyConfig { } -> Option B

4. Quick Check:

   DSC block starts with 'Configuration' [OK]

Hint: DSC configs start with 'Configuration' keyword [OK]

Common Mistakes:

• Using 'Config' instead of 'Configuration'
• Trying to use cmdlets to start config blocks
• Confusing DSC syntax with other PowerShell commands

3. Given this DSC configuration snippet, what will be the output file name generated after running MyConfig?

Configuration MyConfig {
  Node 'localhost' {
    File ExampleFile {
      DestinationPath = 'C:\temp\example.txt'
      Contents = 'Hello DSC'
    }
  }
}
MyConfig

medium

A. localhost.mof

B. MyConfig.ps1

C. example.txt

D. MyConfig.mof

Solution

1. Step 1: Understand DSC output files

   Running a DSC configuration generates a MOF file named after the Node, here 'localhost'.

2. Step 2: Identify the MOF file name

   The MOF file will be 'localhost.mof' because the Node is 'localhost'.

3. Final Answer:

   localhost.mof -> Option A

4. Quick Check:

   DSC MOF file = NodeName.mof [OK]

Hint: DSC MOF file named after Node, not config [OK]

Common Mistakes:

• Assuming MOF file is named after config
• Confusing MOF with script files
• Expecting output as the destination file

4. You wrote this DSC configuration but get an error when running it:

Configuration SampleConfig {
  Node 'localhost' {
    File MyFile {
      DestinationPath = 'C:\temp\file.txt'
      Content = 'Test content'
    }
  }
}
SampleConfig

What is the error in this script?

medium

A. The Node name 'localhost' is invalid

B. The configuration block must end with 'End-Configuration' command

C. The DestinationPath must be a folder, not a file

D. The property 'Content' should be 'Contents' in the File resource

Solution

1. Step 1: Check File resource properties

   The File resource requires the property 'Contents' (plural), not 'Content'.

2. Step 2: Validate other parts

   Node 'localhost' is valid, DestinationPath can be a file path, and no 'End-Configuration' command exists.

3. Final Answer:

   The property 'Content' should be 'Contents' in the File resource -> Option D

4. Quick Check:

   File resource uses 'Contents' property [OK]

Hint: File resource property is 'Contents' plural [OK]

Common Mistakes:

• Using 'Content' instead of 'Contents'
• Thinking Node names must be IP addresses
• Expecting a special end command for configuration

5. You want to ensure a folder C:\Logs always exists on a remote computer using DSC. Which configuration snippet correctly enforces this desired state?

hard

A. Configuration EnsureFolder {
Node 'RemotePC' {
File LogsFolder {
DestinationPath = 'C:\Logs'
Type = 'Directory'
Ensure = 'Present'
}
}
}

B. Configuration EnsureFolder {
Node 'RemotePC' {
Directory LogsFolder {
Path = 'C:\Logs'
State = 'Exists'
}
}
}

C. Configuration EnsureFolder {
Node 'RemotePC' {
File LogsFolder {
DestinationPath = 'C:\Logs'
Ensure = 'Present'
}
}
}

D. Configuration EnsureFolder {
Node 'RemotePC' {
File LogsFolder {
DestinationPath = 'C:\Logs'
Type = 'File'
Ensure = 'Present'
}
}
}

Solution

1. Step 1: Identify correct resource and properties

   To ensure a folder exists, use the File resource with Type='Directory' and Ensure='Present'.

2. Step 2: Check options for correctness

   Configuration EnsureFolder {
     Node 'RemotePC' {
       File LogsFolder {
         DestinationPath = 'C:\Logs'
         Type = 'Directory'
         Ensure = 'Present'
       }
     }
   }

   correctly uses File resource with Type='Directory' and Ensure='Present'.

   Configuration EnsureFolder {
     Node 'RemotePC' {
       File LogsFolder {
         DestinationPath = 'C:\Logs'
         Ensure = 'Present'
       }
     }
   }

   misses Type, D wrongly uses Type='File', B uses a non-existent Directory resource.

3. Final Answer:

   Option A snippet correctly ensures folder presence -> Option A

4. Quick Check:

   File resource + Type='Directory' + Ensure='Present' = folder exists [OK]

Hint: Use File resource with Type='Directory' to create folders [OK]

Common Mistakes:

• Using Type='File' for folders
• Omitting Type property for directories
• Using non-existent 'Directory' resource