Add-LegacyBoot.ps1

<#
.DESCRIPTION
  Powershell script to add DHCP vendor class and policies to allow Legacy BIOS based network booting (PXE) based upon information sent by client detailed in RFC 4578 (https://tools.ietf.org/html/rfc4578) 
.PARAMETERS
  None - execute directly from Powershell 
.VERSION
  1.0 
.AUTHOR
  James Pettigrove 
.COMPATIBILITY
  Windows 7, Windows 10 
.RELEASE DATE
  06/04/2017 
.NOTES 
  v1.0, 20170401 - Initial Version
#>

$dhcpServers = Get-DhcpServerInDC

$className = "PXEClient(Legacy BIOS)"
$classData = "PXEClient:Arch:00000"
$classDesc = "PXEClient:Arch:00000"

$policyName = "Legacy BIOS"
$policyDesc = "Policy for Legacy BIOS based network booting"

[array]$dhcpScopes = (Read-Host "Enter DHCP Scopes (separate with comma) to apply Legacy BIOS boot option").split(",") | %{$_.trim()}

foreach ($dhcpServer in $dhcpServers) {
    Write-Host -ForegroundColor Yellow "Checking if $className exists on $dhcpServer" 
    $classExist = Get-DhcpServerv4Class -ComputerName $dhcpServer -Name $className -Type Vendor -ErrorAction SilentlyContinue
    if (-Not $classExist) {
        Write-Host -ForegroundColor Yellow "Adding $className to $dhcpServer"
        Add-DHCPServerv4Class -ComputerName $dhcpServer -Name $className -Type Vendor -Data $classData -Description $classDesc
    }
    Foreach ($dhcpScope in $dhcpScopes) {
        Write-Host -ForegroundColor Yellow "Adding $policyName to $dhcpScope"
        Add-DhcpServerv4Policy -ComputerName $dhcpServer -ScopeId $dhcpScope -Name $policyName -Description $policyDesc -Enabled $true -Condition OR -VendorClass EQ,"$className*"
        Set-DhcpServerv4OptionValue -ComputerName $dhcpServer -ScopeId $dhcpScope -PolicyName $policyName -OptionId 066 -Value "PXESERVER.local"
	    Set-DhcpServerv4OptionValue -ComputerName $dhcpServer -ScopeId $dhcpScope -PolicyName $policyName -OptionId 067 -Value "SMSBoot\x86\wdsnbp.com"
    }
}