This article will provide details of initiating replication of using WMI in PowerShell. There are a lot of possible methods of starting replication such as using the ‘Active Directory Sites and Services’ console, using the Active Directory PowerShell module and the Sync-ADObject cmdlet.

We will use the MSAD_ReplNeighbor WMI Class for this purpose and specifically the SyncNamingContext method to initiate replication. This class is available in the root\MicrosoftActiveDirectory path on your domain controllers. The commands in this article should be executed on a domain controller. I have made the choice the use the Get-WmiObject in this article as the SyncNamingContext method is not available when using the Get-CimInstance cmdlet, aside from that method all commands can be executed using the Get-CimInstance

In the first code example I will access the MSAD_ReplNeighbor class and retrieve all information. In this article I will use a technique called splatting to input the parameters into the cmdlet:

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$WmiSplat = @{
    Class = 'MSAD_ReplNeighbor'
    Namespace = 'root\MicrosoftActiveDirectory'
}
Get-WmiObject @WmiSplat | Get-Member

The output from this command will display all the available properties and methods, including the SyncNamingContext method that we will use in this article. To view the available partitions for replication, we can use the Select-Object cmdlet to only select the Unique NamingContextDN properties of the returned objects:

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$WmiSplat = @{
    Class = 'MSAD_ReplNeighbor'
    Namespace = 'root\MicrosoftActiveDirectory'
}
Get-WmiObject @WmiSplat | Select-Object -Property NamingContextDN -Unique

Based on this output we determine that the ‘DC=jaapbrasser,DC=com’ partition is the partition we are interested in. In the following code we will filter out only that partion and display a number of selected properties:

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$WmiSplat = @{
    Class = 'MSAD_ReplNeighbor'
    Namespace = 'root\MicrosoftActiveDirectory'
    Filter = "NamingContextDN = 'DC=jaapbrasser,DC=com'"
}
Get-WmiObject @WmiSplat | Select-Object -Property SourceDsaCN,SourceDsaSite,TimeOfLastSyncSuccess,Replicaflags

The first thing that you’ll notice is that the two properties Replicaflags and TimeOfLastSyncSuccess are hard to read, in the following two examples two different approaches are shown to properly convert the TimeOfLastSyncSuccess property to a more human readable output:

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$WmiSplat = @{
    Class = 'MSAD_ReplNeighbor'
    Namespace = 'root\MicrosoftActiveDirectory'
    Filter = "NamingContextDN = 'DC=jaapbrasser,DC=com'"
}
$DateTimeOfLastSyncSuccess = @{
    Name = 'DateTimeOfLastSyncSuccess'
    Expression = {[Management.ManagementDateTimeConverter]::ToDateTime($_.TimeOfLastSyncSuccess)}
}
Get-WmiObject @WmiSplat | Select-Object -Property SourceDsaCN,SourceDsaSite,$DateTimeOfLastSyncSuccess,Replicaflags

Alternatively we can use the Get-CimInstance cmdlet which already provides the converted object:

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$CimSplat = @{
    Class = 'MSAD_ReplNeighbor'
    Namespace = 'root\MicrosoftActiveDirectory'
    Filter = "NamingContextDN = 'DC=jaapbrasser,DC=com'"
}
Get-CimInstance @CimSplat | Select-Object -Property SourceDsaCN,SourceDsaSite,TimeOfLastSyncSuccess,Replicaflags

In order to be able to convert the Replicaflags attribute the value in the property should be converted using the table found in MSAD_ReplNeighbor class article on MSDN. Here is a portion of the the table available on MSDN:

Using the information in this table in combination with the Switch statement the output can be converted in a more human readable format, listing all the flags in text instead of a single integer. In the next example I have also updated the Filter to automatically fill in the current domain name by using the [adsi] type accelerator to select the distinguishedname of the default naming context:

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$WmiSplat = @{
    Class = 'MSAD_ReplNeighbor'
    Namespace = 'root\MicrosoftActiveDirectory'
    Filter = "NamingContextDN = '$(-join ([adsi]'').distinguishedname)'"
}
$DateTimeOfLastSyncSuccess = @{
    Name = 'DateTimeOfLastSyncSuccess'
    Expression = {[Management.ManagementDateTimeConverter]::ToDateTime($_.TimeOfLastSyncSuccess)}
}
$ReadableReplicaFlags = @{
    Name = 'ReadableReplicaFlags'
    Expression = {
        Switch ($_.ReplicaFlags) {
            {$_ -bor 0x10} {'DS_REPL_NBR_WRITEABLE'}
            {$_ -bor 0x20} {'DS_REPL_NBR_SYNC_ON_STARTUP'}
            {$_ -bor 0x40} {'DS_REPL_NBR_DO_SCHEDULED_SYNCS'}
            {$_ -bor 0x80} {'DS_REPL_NBR_USE_ASYNC_INTERSITE_TRANSPORT'}
            {$_ -bor 0x200} {'DS_REPL_NBR_TWO_WAY_SYNC'}
            {$_ -bor 0x800} {'DS_REPL_NBR_RETURN_OBJECT_PARENTS'}
            {$_ -bor 0x10000} {'DS_REPL_NBR_FULL_SYNC_IN_PROGRESS'}
            {$_ -bor 0x20000} {'DS_REPL_NBR_FULL_SYNC_NEXT_PACKET'}
            {$_ -bor 0x200000} {'DS_REPL_NBR_NEVER_SYNCED'}
            {$_ -bor 0x1000000} {'DS_REPL_NBR_PREEMPTED'}
            {$_ -bor 0x4000000} {'DS_REPL_NBR_IGNORE_CHANGE_NOTIFICATIONS'}
            {$_ -bor 0x8000000} {'DS_REPL_NBR_DISABLE_SCHEDULED_SYNC'}
            {$_ -bor 0x10000000} {'DS_REPL_NBR_COMPRESS_CHANGES'}
            {$_ -bor 0x20000000} {'DS_REPL_NBR_NO_CHANGE_NOTIFICATIONS'}
            {$_ -bor 0x40000000} {'DS_REPL_NBR_PARTIAL_ATTRIBUTE_SET'}
        }
    }
}
Get-WmiObject @WmiSplat | Select-Object -Property SourceDsaCN,SourceDsaSite,$DateTimeOfLastSyncSuccess,$ReadableReplicaFlags

By creating both the $DateTimeOfLastSyncSuccess and $ReadableReplicaFlags hashtables, the content can now be displayed in a human readable format, which should make it easier to determine how replication is progressing or where it would be interesting to attempt to initiate replication.

The following example will start replication of the domain partition with all site links of the current server. The ClassName and Filter parameter have been replaced by the Query parameter to illustrate a different approach of querying for this information.

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$WmiSplat = @{
    Namespace = 'root\MicrosoftActiveDirectory'
    Query = "Select * From MSAD_ReplNeighbor Where NamingContextDN = '$(-join ([adsi]'').distinguishedname)'"
}
Get-WmiObject @WmiSplat | ForEach-Object {
    Write-Output "Replicate domain partition: $($_.Domain) from DC: $($_.SourceDsaCN) in the $($_.SourceDsaSite) site"
    $_.SyncNamingContext()
}

This will replicate the domain partition with the defined site links. The Write-Output cmdlet will show which DC and which site replication has been started with. The SyncNamingContext method does accept a single argument as well, an integer that contains the parameters for this method.

For a complete overview of the available parameters please refer to this table:

Using the examples in this article you can now verify when replication last occurred and replicate a Active Directory partition between two or multiple sites. If you have any questions or feedback on this article feel free to use the comments section and for more information on this MSAD_ReplNeighbor WMI class have a look at the following resources: