CredTest

function CredTest($cred, $rekurze){
    $ErrorActionPreference = "Ignore"
    try{#passed cred CAN be $null
    $username = $cred.username
    $password = $cred.GetNetworkCredential().password
    }
    catch{
    }
    $CurrentDomain = "LDAP://" + ([ADSI]"").distinguishedName
    $domain = New-Object System.DirectoryServices.DirectoryEntry($CurrentDomain,$UserName,$Password)
    if ($domain.name -eq $null){
        write-host "Invalid creds." -ForegroundColor Red
        if($rekurze -ne 1){
            Write-Host "Try again"
            $cred = Get-Credential -UserName "domain\" -Message "You need a domain account:";
            CredTest $cred 1 #trying again. Once.
        }
        else{
            Write-Host "Script will be terminated: " -ForegroundColor Red
            [Environment]::Exit(0)
        }
    }
    else{
        write-host "Valid creds. " $cred.UserName -ForegroundColor Green
        return $cred
    }
}
$cred = CredTest $cred
return $cred