C# 通过url获得ip地址

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Diagnostics;

public partial class Admin_BBSYear : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string ip = "www.sina.com";


        this.Label1.Text = CmdPing(ip);
    }
    private static string CmdPing(string strIp)
    {

        Process p = new Process();

        p.StartInfo.FileName = "cmd.exe";

        p.StartInfo.UseShellExecute = false;

        p.StartInfo.RedirectStandardInput = true;

        p.StartInfo.RedirectStandardOutput = true;

        p.StartInfo.RedirectStandardError = true;

        p.StartInfo.CreateNoWindow = true;

        string pingrst;

        p.Start();

        p.StandardInput.WriteLine("ping -n 1 " + strIp);

        p.StandardInput.WriteLine("exit");

        string strRst = p.StandardOutput.ReadToEnd();

        if (strRst.IndexOf("(0% loss)") != -1)
        {
            pingrst = "连接";
            int start = strRst.IndexOf("Reply from");
            int end = strRst.IndexOf(": bytes=");
            pingrst = strRst.Remove(end);
            pingrst = pingrst.Substring(start+10);
        }
        else if (strRst.IndexOf("Destination host unreachable.") != -1)

            pingrst = "无法到达目的主机";

        else if (strRst.IndexOf("Request timed out.") != -1)

            pingrst = "超时";

        else if (strRst.IndexOf("Unknown host") != -1)

            pingrst = "无法解析主机";

        else

            pingrst = strRst;

        p.Close();

        return pingrst;

    }
}