Lookup what AD Site a given IP belongs to. Requires https://www.powershellgallery.com/packages/IP-Calc (https://web.archive.org/web/20230316203737/https://www.powershellgallery.com/packages/IP-Calc/3.1.0/Content/IP-Calc.ps1)

Get-ADSiteByIp.ps1

Function Get-ADSiteByIp {
    param (
        [parameter(Mandatory = $true)][ipaddress]
        [ipaddress]$IP,
        [bool]$CheckForScript = $true # faster
    )
    if ($CheckForScript -eq $true) {
        try { Get-InstalledScript IP-Calc | Out-Null }
        catch {
            Install-Script -Name IP-Calc -Scope CurrentUser -Force -Confirm:$false
            Write-Output "Installing IP-Calc.ps1 from https://www.powershellgallery.com/packages/IP-Calc"
            try { Get-InstalledScript IP-Calc | Out-Null }
            catch {
                Write-Error "Unable to install required IP-Calc script"
                throw
            }
        }
    }
    $domainDN = ($env:USERDNSDOMAIN -split '\.' | % { 'dc=' + $_ } ) -join ','
    $ConfigDN = (([adsi]"LDAP://$DomainDN").objectcategory -split 'Schema,')[-1] # forest-wide support
    $Subnets = [ADSI]"LDAP://CN=Subnets,CN=Sites,$ConfigDN" 

    $selectFilter = @(
        @{n = "SubnetFromSite"; e = { $_.name } }
        @{n = "Site"; e = { ($_.siteObject -split ',' -replace 'CN=', '')[0] } }
        @{n = "PrefixLength"; e = { (IP-Calc.ps1 -CIDR $_.name).PrefixLength } }
    )
    $siteSubnetDetail = $Subnets.Children | select $selectFilter
    
    ($siteSubnetDetail | where { (IP-Calc.ps1 $_.SubnetFromSite ).Compare($IP) } | sort PrefixLength)[-1] | select @{n = "InputIP"; e = { $IP } }, Site, SubnetFromSite
    
}

Get-ADSiteByIp -IP 10.1.1.1 -CheckForScript $false