gistfile1.txt

function Get-TenantId {
    param( 
        [Parameter(Position = 1, Mandatory = $false)]
        [String]$DomainName
       
    )  
    Begin {
        $RequestURL = "https://login.windows.net/{0}/.well-known/openid-configuration" -f $DomainName
        Add-Type -AssemblyName System.Net.Http
        $handler = New-Object  System.Net.Http.HttpClientHandler
        $handler.CookieContainer = New-Object System.Net.CookieContainer
        $handler.AllowAutoRedirect = $true;
        $HttpClient = New-Object System.Net.Http.HttpClient($handler);
        $Header = New-Object System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json")
        $HttpClient.DefaultRequestHeaders.Accept.Add($Header);
        $HttpClient.Timeout = New-Object System.TimeSpan(0, 0, 90);
        $HttpClient.DefaultRequestHeaders.TransferEncodingChunked = $false
        $Header = New-Object System.Net.Http.Headers.ProductInfoHeaderValue("Get-TenantId", "1.1")
        $HttpClient.DefaultRequestHeaders.UserAgent.Add($Header);
        $ClientResult = $HttpClient.GetAsync([Uri]$RequestURL)
        $JsonResponse = ConvertFrom-Json  $ClientResult.Result.Content.ReadAsStringAsync().Result
        return $JsonResponse.authorization_endpoint
    }
}