using System;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        Uri request = new Uri("https://www.one.eplusonline.com");

        string host = request.Host;

​

        Regex regex = new Regex(@"(?<=\.|)\w+\.\w+$");

        Match match = regex.Match(host);

        string hostWithoutPrefix = null;

​

        if (match.Success)

            hostWithoutPrefix = match.Groups[0].Value;

        Console.WriteLine(request.DnsSafeHost);

        Console.WriteLine(hostWithoutPrefix);

    }

}