How to get DateTime from the internet?

Here is a quick code to get the time from the header, works without the need of port 13

public static DateTime GetNistTime()
{
    var myHttpWebRequest = (HttpWebRequest)WebRequest.Create("http://www.microsoft.com");
    var response = myHttpWebRequest.GetResponse();
    string todaysDates = response.Headers["date"];
    return DateTime.ParseExact(todaysDates, 
                               "ddd, dd MMM yyyy HH:mm:ss 'GMT'", 
                               CultureInfo.InvariantCulture.DateTimeFormat, 
                               DateTimeStyles.AssumeUniversal);
}

Things could go wrong. All implements of the code founded above are prone to errors. Sometimes, it works and sometimes it trows a WebExpection error message.

A better implementation:

        try{
            using (var response = 
              WebRequest.Create("http://www.google.com").GetResponse())
                //string todaysDates =  response.Headers["date"];
                return DateTime.ParseExact(response.Headers["date"],
                    "ddd, dd MMM yyyy HH:mm:ss 'GMT'",
                    CultureInfo.InvariantCulture.DateTimeFormat,
                    DateTimeStyles.AssumeUniversal);
        }
        catch (WebException)
        {
            return DateTime.Now; //In case something goes wrong. 
        }

Conclusion:

Having your web app depend on a service that provides accurate date information is critical. I have used one of the code founded here in my app and it really mess things up.

Here is code sample that you can use to retrieve time from NIST Internet Time Service

var client = new TcpClient("time.nist.gov", 13);
using (var streamReader = new StreamReader(client.GetStream()))
{
    var response = streamReader.ReadToEnd();
    var utcDateTimeString = response.Substring(7, 17);
    var localDateTime = DateTime.ParseExact(utcDateTimeString, "yy-MM-dd HH:mm:ss", CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal);
}