How to mark unsuccessful download?

Question

When I'm trying to download a file say of some 900 MB and when I pause download and retry after some time (say hours). Chrome instead of resuming the download just marks the file as completed.

 public HttpURLConnection getConnection(String url, METHOD method)
            throws IOException, SocketException {
        URL server = new URL(url);
        HttpURLConnection httpsconnection = (HttpURLConnection) server.openConnection();
        if (method == METHOD.POST) {
            httpsconnection.setRequestMethod("POST"); //No i18N
            httpsconnection.setFixedLengthStreamingMode(0);
        } else if (method == METHOD.GET) {
            httpsconnection.setRequestMethod("GET"); //No i18N
        }
        httpsconnection.setDoInput(true);
        httpsconnection.setDoOutput(true);
        httpsconnection.setInstanceFollowRedirects(false);
        httpsconnection.setRequestProperty("connection","keep-alive"); //No i18N
        httpsconnection.setRequestProperty("content-length","0"); //No i18N
        httpsconnection.setConnectTimeout(4000);
        httpsconnection.setReadTimeout(30000);
        return httpsconnection;
    }

Am I missing something to set in the header value. When I tried downloading the file from other websites they simply say "Network - Disconnected" and pauses the download which could be resumed after sometime.

Just curious how this pause and resume works with chrome. How my browser client (like Chrome, Firefox) knows about the network interruption. Can someone enlighten me on this?