How to (quickly) check if UNC Path is available

Question

How can I check if a UNC Path is available? I have the problem that the check takes about half a minute if the share is not available :

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Answer 1

I used the ping method suggested above and it did not work for me since I am using OpenDNS Here is a function that worked well for me:

// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
/// 

/// A quick method to test is the path exists 
/// 
/// 
/// 
/// 
public static bool CheckPathExists(string s, int timeOutMs = 120) {
    if (s.StartsWith(@"\\")) {
        Uri uri = new Uri(s);
        if (uri.Segments.Length == 0 || string.IsNullOrWhiteSpace(uri.Host))
            return false;
        if (uri.Host != Dns.GetHostName()) {
            WebRequest request;
            WebResponse response;
            request = WebRequest.Create(uri);
            request.Method = "HEAD";
            request.Timeout = timeOutMs;
            try {
                response = request.GetResponse();
            } catch (Exception ex) {
                return false;
            }
            return response.ContentLength > 0;

            // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
            // Do a Ping to see if the server is there
            // This method doesn't work well using OPenDNS since it always succeeds
            // regardless if the IP is a valid or not
            // OpenDns always maps every host to an IP. If the host is not valid the 
            // OpenDNS will map it to 67.215.65.132
            /* Example:
                C:\>ping xxx

                Pinging xxx.RT-AC66R [67.215.65.132] with 32 bytes of data:
                Reply from 67.215.65.132: bytes=32 time=24ms TTL=55
                */

            //Ping pingSender = new Ping();
            //PingOptions options = new PingOptions();
            // Use the default Ttl value which is 128,
            // but change the fragmentation behavior.
            //options.DontFragment = true;

            // Create a buffer of 32 bytes of data to be transmitted.
            //string data = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
            //byte[] buffer = Encoding.ASCII.GetBytes(data);
            //int timeout = 120;
            //PingReply reply = pingSender.Send(uri.Host, timeout, buffer, options);
            //if (reply == null || reply.Status != IPStatus.Success)
            //    return false;
        }
    }
    return File.Exists(s);
}