Question

I would like to know how to check if a website is offline or online using C#?

Answer 1

Try to hit the URL using HttpWebClient over an HTTP-GET Request. Call GetResponse() method for the HttpWebClient which you just created. Check for the HTTP-Status codes in the Response.

Here you will find the list of all HTTP status codes. If your request status code is statrting from 5 [5xx] which means the site is offline. There are other codes that can also tell you if the site is offline or unavailable.You can compare the codes against your preferred ones from the entire List.

//Code Example

HttpWebRequest httpReq = (HttpWebRequest)WebRequest.Create("http://www.stackoverflow.com");
httpReq.AllowAutoRedirect = false;

HttpWebResponse httpRes = (HttpWebResponse)httpReq.GetResponse();

if (httpRes.StatusCode==HttpStatusCode.NotFound) 
{
   // Code for NotFound resources goes here.
}

// Close the response.
httpRes.Close();