var client = new Client("{key}", "{secret}", "https://api.godaddy.com/api/v1/"); 
// Default is https://api.ote-godaddy.com/api/v1/ (Test link of Godaddy)
try
{
    var response = await client.CheckDomainAvailable(new DomainAvailable
    {
        domain = "google.com"
    });
}
catch (GodaddyException ex) 
{
    //Godaddy Error Message from the Godaddy API
    Console.WriteLine(ex.ErrorResponse.Message);
    //Error Code
    Console.WriteLine(ex.StatusCode);
}