Exam Ref 70-417 Upgrading Your Skills to Windows Server 2012 R2 (2014)

7. After you click Install, the Installation Progress page displays installation progress, results, and messages such as warnings, failures, or postinstallation configuration steps that are required for the roles or features that you installed. In Windows Server 2012 and Windows Server 2012 R2, you can close the Add Roles And Features Wizard while installation is still in progress, and view installation results or other messages in the Notifications area at the top of the Server Manager console. Click the Notifications flag icon to see more details about installations or other tasks that you are performing in Server Manager.

Windows PowerShell Desired State Configuration (DSC)

DSC is an installable feature and server configuration framework that is new to Windows Server 2012 R2. The primary advantage of this new feature is that it lets you ensure that software components of selected servers are present and properly configured.

DSC works through Windows PowerShell. To install the feature, you can use the Add Roles And Features Wizard to add the component of the Windows PowerShell feature named “Windows PowerShell Desired State Configuration.” To add the feature from an elevated Windows PowerShell prompt, type Install-WindowsFeature DSC-Service.

What’s new and different about DSC is that it’s a declarative management system. This means that, instead of performing particular tasks on one or more target servers, you declare through DSC a desired end-state for those target servers. If the servers already meet the desired configuration, no errors are generated. If the servers do not meet the desired configuration, they individually and automatically make the changes needed to bring themselves into compliance with the desired end-state.

You can use DSC to manage target servers running only Windows Server 2012 R2 by default. However, if you install Windows Management Framework 4.0 on servers running Windows Server 2008 R2 and Windows Server 2012, you can manage these servers through DSC as well.

There are three steps to using DSC after you install it on the management and target servers:

1. Define the desired configuration by creating a new Configuration function in the Windows PowerShell ISE tool. You give this function a name of your choice and use it to invoke DSC resources such as WindowsFeature, File, Group, or Service. You use the syntax of each DSC resource to define the specific components you want to ensure are configured properly on the target server or servers.

2. Enact the configuration by calling (typing) your new function at a Windows PowerShell prompt. This step turns your desired configuration into a Managed Object Format (MOF) file that is usable with the Start-DscConfiguration cmdlet. (Start-DscConfiguration is the cmdlet you use to apply configurations to servers through DSC.) The MOF file is created beneath the current directory in a new subdirectory with the name of your new function.

3. Run the following Windows PowerShell command:

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

where FunctionName is the name of your Configuration function. Note that the –Wait and –Verbose parameters are merely recommended and not required. Also note that if the target server is remote, you first need need to copy the MOF file to the remote server before you can run Start-DscConfiguration.

The following is an example Configuration function named EnsureIIS. Its purpose is to ensure that the IIS role is installed on the server named Web1. Read the code along with the comments to get an idea of the basic syntax you might need to understand for the 70-417 exam.

Configuration EnsureIIS
{
# First you have to specify one ore more servers with the keyword "Node."
# A node is a server on which the configuration will take place.
Node "Web1"
{
# After specifying the node, you have to specify one or more DSC resources.
# WindowsFeature is one of the many built-in DSC resources.
# Each DSC resource has specific syntax for configuring components.
WindowsFeature IIS
{
Ensure = "Present" # You would set this to "Absent" to uninstall the role.
Name = "Web-Server"
}
}
}

After you run this code, you would type EnsureIIS at the same prompt. This step creates an MOF file in a new directory named EnsureIIS beneath your current directory.

Finally, you would run the following command at the same prompt (or another prompt pointed at the same location in the file structure):

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

This final step would install IIS if it were not already installed.

What do you need to know about DSC for the 70-417 exam? First of all, you need to understand the scenarios in which DSC is useful. The key concept here is that DSC provides declarative management. This means that with DSC you can enforce a desired configuration on remote servers without generating an error if one or more of those target servers is already in compliance. So, if you see a question scenario that calls for a way to manage servers by specificying a target state for those servers, you should suspect that DSC is at least part of the answer.

Next, you should also remember that DSC includes resources for supporting the following configuration components:

Enabling or disabling server roles and features

Managing registry settings

Managing files and folders

Starting, stopping, and managing processes and services

Managing local user and group accounts

Deploying new software packages

Managing environment variables

Running Windows PowerShell scripts

Third, you should understand the basic steps required to configure a server through DSC. For example, you might be presented with a scenario in which you have already created a Configuration function called MyConfig, and you will be asked which step to take next. (Answer: Type MyConfig. Don’t use Start-DscConfiguration yet).

Finally, it is possible that you will need to understand some very simple DSC code, especially the basic syntax for DSC resources. Remember above all that the line Ensure = “Present” in a resource block of code ensures that a feature is installed and Ensure = “Absent” ensures that a feature is not installed.

DSC Resources

Aside from the WindowsFeature DSC resource in the code example above, you should also learn to understand basic syntax for the File, Group, and Service resources. The following is an example of using the File DSC resource, which could appear as a resource block in a Configuration function beneath “Node”:

File DirectoryCopy
{
Ensure = "Present" # You can also set Ensure to "Absent."
Type = "Directory" # Default is "File"
Recurse = $true # Ensure presence of subdirectories, too.
SourcePath = "C:\Users\Public\Documents\DSCDemo\DemoSource"
DestinationPath = "C:\Users\Public\Documents\DSCDemo\DemoDestination"
}

The following is an example of the Group resource:

Group GroupExample
{
# This will remove TestGroup, if present.
# To create a new group, set Ensure to "Present."
Ensure = "Absent"
Name = "TestGroup"
}

And the following is an example of the Service resource:

Service ServiceExample
{
Name = "TermService"
StartupType = "Manual"
}