[Delphi]检查上网线路的DNS性能

说明：近期发现某个电信运营商上网宽带的DNS服务的一个问题：DNS查询频率有限制,  而且使用其他DNS服务器不解决问题。如果这种宽带只是在家庭里面使用，DNS的查询频度还没达到上限，但如果是在单位里面使用，当使用人数较多时，DNS查询频率会大于限制的频率，造成上网卡顿的问题。在遇到上网卡顿，但Ping又正常时，可以用此程序检查上网线路的DNS性能。需用运营商提供的DNS服务器的ip地址替换上图中的DNS服务器ip地址。让查询次数达到1万次以上，看看有没有超时的现象。如果超时较多，就应该联系运营商解决了。 

 uMain.pas:

unit uMain;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants,
  System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs,
  Vcl.StdCtrls, Vcl.ComCtrls, Vcl.ExtCtrls, RzPrgres;

type
  TForm1 = class(TForm)
    ButtonQuery: TButton;
    EditCount: TLabeledEdit;
    EditDNS: TLabeledEdit;
    EditFreq: TLabeledEdit;
    ProgressBar: TRzProgressBar;
    EditTimeOut: TLabeledEdit;
    procedure ButtonQueryClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    TotalCnt, TimeOutCnt: Integer;
    StartTime: TDateTime;
    procedure WmProc(var Msg: TMessage); message WM_User;
  public
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses uDNSQueryThread;

procedure TForm1.FormCreate(Sender: TObject);
begin
  ReportMemoryLeaksOnShutDown := True;
end;

procedure TForm1.ButtonQueryClick(Sender: TObject);
begin
  if ButtonQuery.Caption = '查询' then
  begin
    TotalCnt := 0;
    TimeOutCnt := 0;

    EditCount.Text := '';
    EditFreq.Text  := '';
    EditTimeOut.Text := '0';

    StartTime := Now;
    ProgressBar.PartsComplete := 0;
    DNSQueryThread := TDNSQueryThread.Create(EditDNS.Text);
    ButtonQuery.Caption := '停止'
  end
  else
  begin
    DNSQueryThread.Terminate;
    ButtonQuery.Caption := '查询';
  end;
end;

procedure TForm1.WmProc(var Msg: TMessage);
var
  P: Integer;
  Seconds: Real;
begin
  Inc(TotalCnt);
  EditCount.Text := TotalCnt.ToString;

  Seconds := 86400 * (Now - StartTime);
  if Seconds <> 0 then
    EditFreq.Text := Round(TotalCnt/Seconds).ToString;

  if Msg.LParam = -1 then
  begin
    Inc(TimeOutCnt);
    EditTimeOut.Text := TimeOutC