Pascal (Lazarus/Delphi)

Use Public DNS Servers (Google and Cloudfare)

See more DNS Examples

Demonstrates how to use Google and Cloudfare nameservers for all DNS lookups within Chilkat.

Note: This example requires Chilkat v9.5.0.96 or later.

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Dns;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  dns: TDns;
  supportsTls: Boolean;

begin
  //  The new Chilkat DNS class is a singleton that allows an applicaton to select 
  //  the DNS nameservers used throughout Chilkat.

  //  "singleton" means that all Chilkat DNS object instances work with a single
  //  copy of internal DNS settings that are application wide.

  //  Chilkat does DNS lookups internally whenever a domain name is passed to a Chilkat method, or when the domain
  //  name is part of a URL passed to a Chilkat method.  It could be in HTTP, Ftp2, SSH, IMAP, Socket, etc.

  //  This exampel will show how to use the Cloudfare and Google DNS servers.
  //  
  //  Google Public DNS:
  //    - Primary DNS: 8.8.8.8
  //    - Secondary DNS: 8.8.4.4
  //    Google Public DNS is known for its speed and reliability. It's operated by Google and is widely used by many internet users.

  //  Cloudfare Public DNS:
  //    - Primary DNS: 1.1.1.1
  //    - Secondary DNS: 1.0.0.1
  //    Cloudfare Public DNS is also known for its speed and reliability, and is also widely used.

  dns := TDns.Create;

  //  Indicate our TLS preference:
  //  0: No TLS
  //  1: Prefer TLS if possible
  //  2: Require TLS
  dns.TlsPref := 0;

  //  If you choose "No TLS", then all DNS requests will use UDP, or TCP for those requests with large responses.
  //  Choosing "No TLS" provides the fastest DNS lookups, and is generally what you're already doing.

  //  If you choose "Prefer TLS if possible", then Chilkat will use DNS over TLS for those nameservers that
  //  support TLS.

  //  If you choose "Require TLS", then Chilkat will ignore nameservers that don't support TLS,
  //  and all DNS communications will occur over private and secure TLS connections.

  //  When you specify a nameserver to be used, you'll tell Chilkat whether it supports DNS or not.
  //  Here' we're setting the nameservers to Google and Cloudfare.
  //  They both support TLS, but since we set our TLS preference = 0, Chilkat will not use TLS.
  //  (If we set our TLS preference equal to 1 or 2, then Chilkat will use TLS for Google and Cloudfare DNS.)

  //  First, make sure we remove all existing nameservers.
  dns.RemoveAllNameservers();

  //  Add the Google and Cloudfare nameservers.
  supportsTls := True;
  dns.AddNameserver('1.1.1.1',supportsTls);
  dns.AddNameserver('8.8.8.8',supportsTls);
  dns.AddNameserver('1.0.0.1',supportsTls);
  dns.AddNameserver('8.8.4.4',supportsTls);

  //  That's it.  Now all DNS lookups in Chilkat will use the above nameservers.


  dns.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.