Desired State Configuration (DSC) basics in PowerShell - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Desired State Configuration (DSC) in PowerShell?

DSC is a management platform in PowerShell that helps you define and maintain the configuration of your computers automatically, ensuring they stay in a desired state.

beginner

What is a DSC Configuration script?

A DSC Configuration script is a special PowerShell script that defines the desired settings for a computer or environment using a declarative syntax.

beginner

What does the 'Node' keyword do in a DSC Configuration?

The 'Node' keyword specifies which computer(s) the configuration applies to. It can be a single computer or multiple computers.

beginner

What is a 'Resource' in DSC?

A Resource is a building block in DSC that defines how to configure a specific part of the system, like installing software or setting a service state.

beginner

How do you apply a DSC configuration to a computer?

You compile the configuration script to create a .mof file, then use the Start-DscConfiguration cmdlet to apply it to the target computer.

What is the main purpose of Desired State Configuration (DSC)?

A To monitor network traffic

B To write scripts that run only once

C To create user accounts manually

D To automatically keep computers in a defined configuration state

DSC ensures computers stay in the desired configuration automatically.

Which PowerShell keyword defines the target computers in a DSC configuration?

A Resource

B Node

C Configuration

D Apply

The 'Node' keyword specifies the target computers for the configuration.

What file type is generated after compiling a DSC configuration script?

A .mof

B .txt

C .xml

D .ps1

DSC compiles configuration scripts into .mof files for applying configurations.

Which cmdlet applies a DSC configuration to a computer?

A Set-ExecutionPolicy

B Invoke-Command

C Start-DscConfiguration

D New-Item

Start-DscConfiguration applies the compiled DSC configuration to the target.

In DSC, what is a Resource used for?

A To define how to configure a system component

B To store user data

C To write logs

D To schedule tasks

Resources define how to configure specific parts of the system in DSC.

Explain the basic workflow of creating and applying a DSC configuration.

Think about the steps from writing to applying the configuration.

Describe what a DSC Resource is and give an example of its use.

Resources are like building blocks for configurations.

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