TPing.OnDNSLookupDone

Main page -> ICS component reference -> TPing -> OnDNSLoopupDone

Definition

 event OnDNSLookupDoneSender:TObject; Error: Word;

Description

If the address property is specified as DNS address instead of an IP address, a DNS lookup will be performed by the ping component. Be aware that this information is being queried in the background. After this DNS lookup completed, this OnDNSLookupDone event will be fired.

The DNSResult property will contain the IPv4 or IPv6 address of the remote host specified in address property.

Example

<syntaxhighlight lang="delphi">

 unit MainForm;
 
 interface
   
 uses
   Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes,
   Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs,
   OverbyteIcsWndControl, OverbyteIcsPing, Vcl.StdCtrls;
   
 type
   TForm1 = class(TForm)
     Ping1: TPing;
     Button1: TButton;
     procedure Ping1DnsLookupDone(Sender: TObject; Error: Word);
     procedure Button1Click(Sender: TObject);
   private
   public
   end;
 
 var
   Form1: TForm1;
 
 implementation
 
 {$R *.dfm}
 
 procedure TForm1.Button1Click(Sender: TObject);
 begin
   Ping1.DnsLookup('wikipedia.org');
 end;
 
 procedure TForm1.Ping1DnsLookupDone(Sender: TObject; Error: Word);
 begin
   if Error = 0 then
     ShowMessage(Ping1.DnsResult);
   else
     ShowMessage('Error on DNS lookup. Code: ' + IntToStr(Error));
 end;
 
 end.
 

</syntaxhighlight>

Best practices

Process the contents of the DNSResult property in OnDNSLookupDone event if the Error parameter of this event is 0.