PowerShell: List All Subnets in Sites & Services

January 16, 2018|Active Directory, Microsoft, PowerShell

The below PowerShell script will generate a CSV file that lists each replication subnet in Active Directory Sites and Services. The list includes the site associated with the subnet, and whether or not a domain controller is in the site.

This script assumes you have a healthy AD and that your domain controllers are online.

## Get a list of all domain controllers in the forest
$DcList = (Get-ADForest).Domains | ForEach { Get-ADDomainController -Discover -DomainName $_ } | ForEach { Get-ADDomainController -Server $_.Name -filter * } | Select Site, Name, Domain

## Get all replication subnets from Sites & Services
$Subnets = Get-ADReplicationSubnet -filter * -Properties * | Select Name, Site, Location, Description

## Create an empty array to build the subnet list
$ResultsArray = @()

## Loop through all subnets and build the list
ForEach ($Subnet in $Subnets) {

    $SiteName = ""
    If ($Subnet.Site -ne $null) { $SiteName = $Subnet.Site.Split(',')[0].Trim('CN=') }

    $DcInSite = $False
    If ($DcList.Site -Contains $SiteName) { $DcInSite = $True }

    $RA = New-Object PSObject
    $RA | Add-Member -type NoteProperty -name "Subnet"   -Value $Subnet.Name
    $RA | Add-Member -type NoteProperty -name "SiteName" -Value $SiteName
    $RA | Add-Member -type NoteProperty -name "DcInSite" -Value $DcInSite
    $RA | Add-Member -type NoteProperty -name "SiteLoc"  -Value $Subnet.Location
    $RA | Add-Member -type NoteProperty -name "SiteDesc" -Value $Subnet.Description

    $ResultsArray += $RA

}

## Export the array as a CSV file
$ResultsArray | Sort Subnet | Export-Csv .\AD-Subnets.csv -nti