param([array]$serverlist=$null)# This script solved a specific problem for me - Identification of a Domain Controller's subnet membership in Active Directory (even if not in the same site,# or a "catch-all" subnet - where the IPV4 Network cannot be used, and IP Address Ranges must be used to determine).
It checks the local AD Site for network match, then all other AD Sites for network match, then all AD Sites for "catch-all" match
After some research, I found helpful articles on MSDN, and MSDN Blogs
This script demonstrates IPv4 Address calculations, enumerating Domains, DCs and Sites within Active Directory (and still needs to be optimized to not# re-query AD Data as it runs).
References
MSDN - IPAddress Class - https://msdn.microsoft.com/en-us/library/system.net.ipaddress(VS.80).aspx# MSDN - Forest Class - https://msdn.microsoft.com/en-us/library/system.directoryservices.activedirectory.forest(VS.80).aspx# MSDN Blogs - Knom's Developer Corner - https://blogs.msdn.com/knom/archive/2008/12/31/ip-address-calculations-with-c-subnetmasks-networks.aspx
This script is provided "AS IS" with no warranties, and confers no rights.# Use of any portion or all of this script are subject to the terms specified at# https://www.microsoft.com/info/cpyright.htm.
Write-Host "";Write-Host "";Write-Host "Process-SubnetDefinitions.ps1";Write-Host "";Write-Host "";If($serverlist -eq $null) { Write-Host "You must specify the target dc using the serverlist switch. e.g., .\Process-SubnetDefinitions.ps1 -serverlist:'servername'"; break; }Write-Host "Retrieving IP Address details and Subnet defintions for listed servers";$erroractionpreference = "SilentlyContinue";$error.Clear();# For use with [System.Net.IpAddress]::Parse which cannot read the native powershell byte array, so we Parse and create a string (returns a string, e.g. "255.255.255.0")
function FormatBinaryMask{    param([byte[]]$binaryMask)    $string = [string]::Empty;    for([int]$i = 0; $i -lt 4; $i++)    {        if($i -eq 0)        {            $string = $string + $binaryMask[$i].ToString();        }        else        {            $string = $string + "." + $binaryMask[$i].ToString();        };    };    return $string;}# Specify the number of bits for the Host to return the subnet mask (returns an IPAddress object)
function SubnetMaskByHostBitLength{    param([int]$hostPartLength)        $netPartLength = 32 - $hostPartLength;        if ($netPartLength -lt 2) { Write-Error "Too many hosts for IPv4"; break; };        $binaryMask = New-Object byte[] 4;        for([int]$i = 0; $i -lt 4; $i++)    {        if(($i * 8 + 8) -le $netPartLength) { $binaryMask[$i] = [byte]255; }        elseif(($i * 8) -gt $netPartLength) { $binaryMask[$i] = [byte]0; }        else        {            $oneLength = $netPartLength - $i * 8            $binaryDigit = [String]::Empty.PadLeft($oneLength, '1').PadRight(8, '0')            $binaryMask[$i] = [System.Convert]::ToByte($binaryDigit, 2)        };    };    return [System.Net.IPAddress]::Parse((FormatBinaryMask $binaryMask));}# Specify the number of bits for the Network to return the subnet mask (returns an IPAddress object)
function SubnetMaskByNetBitLength{    param([int]$netPartLength)    $hostPartLength = 32 - $netPartLength;    return SubnetMaskByHostBitLength($hostPartLength);}# Performs a boolean AND between the IP Address and the subnet mask to return the Network Address, e.g. 192.168.1.0 (returns an IP Address object)
function GetNetworkAddress{    param([System.Net.IPAddress]$address, [System.Net.IPAddress]$subnetMask)    [byte[]]$ipAdressBytes = $address.GetAddressBytes();    [byte[]]$subnetMaskBytes = $subnetMask.GetAddressBytes();    if ($ipAdressBytes.Length -ne $subnetMaskBytes.Length) { Write-Error "Lengths of IP address and subnet mask do not match"; break; };    $broadcastAddress = New-Object byte[] $ipAdressBytes.Length;        for ([int]$i = 0; $i -lt $broadcastAddress.Length; $i++)    {        $broadcastAddress[$i] = [byte]($ipAdressBytes[$i] -band ($subnetMaskBytes[$i]));    };    return [System.Net.IPAddress]::Parse((FormatBinaryMask $broadcastAddress));}# Performs a boolean AND between the the subnet mask and 255.255.255.255 to return a filter for determining the number of usable addresses and those # limits within a network, e.g. would return 0.0.0.255 for the subnet mask 255.255.255.0 (returns an IP Address object)
function GetNetworkUsableAddressRangeFilter{    param([System.Net.IPAddress]$subnetMask)    $topend = [System.Net.IPAddress]::Parse("255.255.255.255");    [byte[]]$subnetMaskBytes = $subnetMask.GetAddressBytes();    [byte[]]$topendBytes = $topend.GetAddressBytes();    $broadcastAddress = New-Object byte[] $subnetMaskBytes.Length;        for ([int]$i = 0; $i -lt $broadcastAddress.Length; $i++)    {        $broadcastAddress[$i] = [byte]($topendBytes[$i] -bxor ($subnetMaskBytes[$i]));    };    return [System.Net.IPAddress]::Parse((FormatBinaryMask $broadcastAddress));}# Compares the networks of 2 sets of IP Address and subnet masks to determine if they are on the same network
function  {    param([string]$address1, [string]$subnetMask1, [string]$address2, [string]$subnetMask2)    $network1 = GetNetworkAddress ([System.Net.IPAddress]::Parse($address1)) ([System.Net.IPAddress]::Parse($subnetMask1));    $network2 = GetNetworkAddress ([System.Net.IPAddress]::Parse($address2)) ([System.Net.IPAddress]::Parse($subnetMask2));    return $network1.Equals($network2);}$results = @();$forest = [System.DirectoryServices.ActiveDirectory.Forest]::GetCurrentForest();foreach($server in $serverlist){    $error.Clear();    $result = New-Object PSObject | Select-Object "DCName","IPAddress","SubnetMask","Site","SiteSubnets",      "SiteWithMatchingSubnet","MatchingSiteSubnet","MatchFound","CriticalError","ErrorDetails";    $result.DCName = $server;    $wmi = Get-WmiObject -computer $server Win32_NetworkAdapterConfiguration -filter "IPEnabled='true'";    If ($error)        {            $result.CriticalError = $true;            $result.ErrorDetails = $error[0];            $error.Clear();            }        else        {            $result.CriticalError = $false;            $result.ErrorDetails = $null;            $result.IPAddress = $wmi.IPAddress[0];            $result.SubnetMask = $wmi.IPSubnet[0];                    };    foreach($domain in $forest.Domains)    {        foreach($dc in $domain.DomainControllers)        {            if($dc.Name.ToLower().Contains($server.ToLower()))            {                $result.Site = $dc.SiteName;            };        };    };        foreach($site in $forest.Sites)    {        if($site.Name -eq $result.Site)        {            $result.SiteSubnets = $site.Subnets;        };    };    $result.SiteWithMatchingSubnet = $null;    $result.MatchingSiteSubnet = $null;    $result.MatchFound = $false;    $results += $result;};# Search Local Site Subnets for explicit match
Write-Host "";Write-Host "Processing DC Local Sites First for explicit match....";foreach($result in $results){    If($result.CriticalError -eq $false)    {        Write-Host "";        Write-Host (" Working on Server: {0}" -f $result.DCName);        foreach($subnet in $result.SiteSubnets)        {            if($result.MatchFound -eq $false)            {                $res = $false;                $netaddress = $subnet.Name.Split("/");                $res = IsInSameSubnet $result.IPAddress $result.SubnetMask $netaddress[0] (SubnetMaskByNetBitLength $netaddress[1]);                If($res)                {                    Write-Host "  Match Found";                    $result.SiteWithMatchingSubnet = $result.Site;                    $result.MatchingSiteSubnet = $subnet.Name;                    $result.MatchFound = $true;                };            };        };    };}$continue = $false;foreach($result in $results){    if($result.MatchFound -eq $false) { $continue = $true; };}if($continue -eq $false) { $results; break; };# Search All other Sites for explicit match
Write-Host "";Write-Host "Processing All Other Sites for explicit match....";foreach($result in $results){    if($result.CriticalError -eq $false)    {        Write-Host "";        Write-Host (" Working on Server: {0}" -f $result.DCName);        foreach($site in $forest.Sites)        {            $found = $false;            if ($site.Name -ne $result.Site)            {                Write-Host ("  Checking Site: {0}" -f $site.Name);                foreach($subnet in $site.Subnets)                {                    $res = $false;                    $netaddress = $subnet.Name.Split("/");                    $res = IsInSameSubnet $result.IPAddress $result.SubnetMask $netaddress[0] (SubnetMaskByNetBitLength $netaddress[1]);                    If($res)                    {                        Write-Host "   Match Found";                        $result.SiteWithMatchingSubnet = $site.Name;                        $result.MatchingSiteSubnet = $subnet.Name;                        $result.MatchFound = $true;                    };                    };            };            if($result.MatchFound) { break; };        };    };};$continue = $false;foreach($result in $results){    if($result.MatchFound -eq $false) { $continue = $true; };}if($continue -eq $false) { $results; break; };# Search all subnets for "catch-all" match
Write-Host "";Write-Host "Processing All Other Sites for Catch-All subnet match....if required....";foreach($server in $results){    If($server.CriticalError -eq $false)    {        Write-Host "";        write-host (" Working on Server: {0}" -f $server.DCName);        while($server.MatchFound -eq $false)        {            foreach($site in $forest.Sites)            {                if($server.MatchFound -eq $false)                {                    Write-Host ("  Checking Site: {0}" -f $site.Name);                    foreach($subnet in $site.Subnets)                    {                        if($server.MatchFound -eq $false)                        {                                $lastaddress = new-object byte[] 4;                            $netaddress = $subnet.Name.Split("/");                            If($netaddress[0] -le 8)                            {                                $netmask = SubnetMaskByNetBitLength $netaddress[1];                                $filter = GetNetworkUsableAddressRangeFilter $netmask;                                $i = 0;                                foreach($byte in $filter.GetAddressBytes())                                {                                    if ($byte -eq 0)                                    {                                        $lastaddress[$i] = [System.Net.IPAddress]::Parse($netaddress[0]).GetAddressBytes()[$i];                                                }                                    else                                    {                                        $lastaddress[$i] = ([System.Net.IPAddress]::Parse($netaddress[0])).GetAddressBytes()[$i] + $byte;                                    };                                    $i++;                                };                                $serverip = ([System.Net.IPAddress]::Parse($server.IPAddress)).GetAddressBytes();                                If(($serverip[0] -ge $([System.Net.IPAddress]::Parse($netaddress[0])).GetAddressBytes()[0]) -and ($serverip[0] -le $lastaddress[0]))                                {                                    If(($serverip[1] -ge $([System.Net.IPAddress]::Parse($netaddress[0])).GetAddressBytes()[1]) -and ($serverip[1] -le $lastaddress[1]))                                    {                                        If(($serverip[2] -ge $([System.Net.IPAddress]::Parse($netaddress[0])).GetAddressBytes()[2]) -and ($serverip[2] -le $lastaddress[2]))                                        {                                            If(($serverip[3] -ge $([System.Net.IPAddress]::Parse($netaddress[0])).GetAddressBytes()[3]) -and ($serverip[3] -le $lastaddress[3]))                                            {                                                Write-Host "   Match Found";                                                $server.MatchingSiteSubnet = ("{0}/{1}" -f ($netaddress[0], $netaddress[1]));                                                $server.SiteWithMatchingSubnet = $subnet.Site;                                                $server.MatchFound = $true;                                            };                                        };                                    };                                };                                     };                        };                            };                };            };        };    };};$results;$erroractionpreference = "Continue";