Suppress error "Hostname could not be resolved"

This is my code:

string Url = "http://illution.dk/";
WebClient Http = new WebClient();
Http.DownloadStringAsync(new Uri(Url));
Http.DownloadStringCompleted += new DownloadStringCompletedEventHandler(GetModelTypeResponse);

If I run this on a machine with no internet connection an error will be thrown. "Hostname could not be resolved"

Is there any way I can remove this error message? Or check if there isn't an internet connection?

Edit 1

try
{
ComputerInfo ComputerInfoComp = new ComputerInfo();
string Url = "http://illution.dk/"
WebClient Http = new WebClient();
Http.DownloadStringAsync(new Uri(Url));
Http.DownloadStringCompleted += new         DownloadStringCompletedEventHandler(GetModelTypeResponse);
ComputerInfoComp = null;
}
catch (Sys开发者_如何学Gotem.Net.WebException e)
{
//
}

Check e.Error in your GetModelTypeResponse handler method. If e.Error is of type WebException then check webException.Status value. The value will be WebExceptionStatus.NameResolutionFailure in case of "Hostname could not be resolved" exception

public void GetModelTypeResponse(object sender, DownloadStringCompletedEventArgs e)
{
    var webException = e.Error as WebException;
    if (webException != null && 
        webException.Status == WebExceptionStatus.NameResolutionFailure)
    {
        // log
        return; // ignore
    }

    // proceed
    ..
}

Yes, by catching that particular exception. See http://msdn.microsoft.com/en-us/library/ms173160(v=vs.80).aspx

Put your code in a try...catch block. Google exceptions for more information.