Translate NT format (NetBIOS) Domain name to Distinguished Name (DNS Domain Name)

I'm currently using the below code to convert NT format (NetBIOS) domain names to Distinguished name (DNS Domain name).

NameTranslate object works great in my code... until I try to use the same code over my work VPN... resulting in an exception

The remote procedure call failed. (HRESULT: 0x800706BE)

I'm looking for an alternate way to do this (any way at all in a PowerShell script without having problems over VPN). I'm looking for a solution that doesn't require 3rd party PS modules or assembly dependencies, with the fewest lines of code.

$Domain = "SF"
$objTrans = New-Object -comObject "NameTranslate"
$objNT = $objTrans.GetType()
$objNT.InvokeMember("Init", "InvokeMethod", $Null, $objTrans, (3, $Null))
$objNT.InvokeMember("Set", "InvokeMethod", $Null, $objTrans, (3, "$Domain\"))
$DNSDomain = $objNT.InvokeMember("Get", "InvokeMethod", $Null, $objTrans, 1)

EDIT: For those who don't have much experience with NameTranslate (and also need a bigger picture what I'm trying to do):

I need to validate user-input'ed AD username/password, e.g., 'SF\MKANET' for the username. The best way I know to validate an AD account in PowerShell is with the below code. I need a programmatic way to take the "SF" this user-inputed text example; and, convert it to a format that can be used where $DNSDomain goes below. If someone has alternate solution with I could use to do the same thing, please let me know.

$DOM = New-Object System.DirectoryServices.DirectoryEntry($DNSDomain,$UserName,$Password)
if ($DOM.name -ne $null) {$CredentialValid = $True}