List Sites and Subnets in Active Directory using PowerShell

How to list sites and subnets in Active Directory using Powershell.  This script determines the path to the configuration partition in your Active Directory, enumerates the site objects and retrieves the name and description of each.  It then enumerates the subnets, identifies which site the subnet belongs to, then outputs the sorted results to the screen.

The script serves as an example of how to use ldap://RootDSE/ to connect to your AD without hard-coding domain names, and how to enumerate children of [adsi] objects.

$siteDescription=@{}
$siteSubnets=@{}
$subnetDescription=@{}
$sitesDN="LDAP://CN=Sites," + $([adsi] "LDAP://RootDSE").Get("ConfigurationNamingContext")
$subnetsDN="LDAP://CN=Subnets,CN=Sites," + $([adsi] "LDAP://RootDSE").Get("ConfigurationNamingContext")
#get the site names and descriptions
foreach ($site in $([adsi] $sitesDN).psbase.children){
 if($site.objectClass -eq "site"){
  $siteName=([string]$site.cn).toUpper()
  $siteDescription[$siteName]=$site.description[0]
  $siteSubnets[$siteName]=@()
 }
}
#get the subnets and associate them with the sites
foreach ($subnet in $([adsi] $subnetsDN).psbase.children){
 $subnetDescription[[string]$subnet.cn]=$subnet.description[0]
 $site=[adsi] "LDAP://$($subnet.siteObject)"
 if($site.cn -ne $null){
  $siteName=([string]$site.cn).toUpper()
  $siteSubnets[$siteName] += $subnet.cn
 }else{
  $siteDescription["Orphaned"]="Subnets not associated with any site"
  if($siteSubnets["Orphaned"] -eq $null){ $siteSubnets["Orphaned"] = @() }
  $siteSubnets["Orphaned"] += $subnet.cn
 }
}
#write output to screen
foreach ($siteName in $siteDescription.keys | sort){
 "$siteName  $($siteDescription[$siteName])"
 foreach ($subnet in $siteSubnets[$siteName]){
  "`t$subnet $($subnetDescription[$subnet])"
 }
}

The syntax above is intentionally verbose, so that you can see what's going on in the code.  However, if you're one of those people that prefer a fluent pipeline, here you go.

$siteDescription=@{}
$siteSubnets=@{}
$subnetDescription=@{}
$sitesDN = "LDAP://CN=Sites," + $([adsi] "LDAP://RootDSE").Get("ConfigurationNamingContext")
$subnetsDN = "LDAP://CN=Subnets,CN=Sites," + $([adsi] "LDAP://RootDSE").Get("ConfigurationNamingContext")
([adsi] $sitesDN).children | ?{$_.objectClass -eq "site"} | %{ $siteName = ([string]$_.cn).toUpper(); $siteDescription[$siteName] = $_.description[0]; }
([adsi] $subnetsDN).children | %{ $siteSubnets[[string](([adsi] "LDAP://$($_.siteObject)").cn)] += $_.cn; $subnetDescription[[string]$_.cn]=$_.description[0] }
$siteDescription.keys | sort | %{ "$_  $($siteDescription[$_])"; $siteSubnets[$_] | %{"`t$_ $($subnetDescription[$_])"} }

Related Posts:

• Backup DFS Namespaces Using PowerShell
• Translate Active Directory Name Formats Using PowerShell
• List Linux Users in Active Directory Using PowerShell
• Enable Trust for Delegation in Active Directory Using PowerShell
• TCP/IP Subnet Math with PowerShell - What AD Site is that Server in?
• List Sites and Subnets in Active Directory with PowerShell
• Find Disabled Users in Active Directory with PowerShell
• List Forest-wide Group Memberships with PowerShell
• Find Old Computer Accounts in AD with PowerShell
• List SPNs in Active Directory with PowerShell
• List Domain Controllers in Active Directory