Delphi DLL

DNS Query MX Records

See more DNS Examples

Shows how to perform a DNS query to retrieve MX records.

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

Delphi DLL

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Dns, JsonObject;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
dns: HCkDns;
json: HCkJsonObject;
name: PWideChar;
ttl: Integer;
pref: Integer;
domain: PWideChar;
i: Integer;
count_i: Integer;

begin
success := False;

dns := CkDns_Create();

json := CkJsonObject_Create();
CkJsonObject_putEmitCompact(json,False);

success := CkDns_Query(dns,'MX','somebody@gmail.com',json);
if (success = False) then
  begin
    Memo1.Lines.Add(CkDns__lastErrorText(dns));
    Exit;
  end;

Memo1.Lines.Add(CkJsonObject__emit(json));

// Sample response.
// Parsing code below..

// -------------------------------------------------------------------------------
// Note: Chilkat will return the results sorted by "pref" from lowest to highest.
// -------------------------------------------------------------------------------

// {
//   "answer": {
//     "mx": [
//       {
//         "name": "gmail.com",
//         "ttl": 491,
//         "pref": 5,
//         "domain": "gmail-smtp-in.l.google.com"
//       },
//       {
//         "name": "gmail.com",
//         "ttl": 491,
//         "pref": 10,
//         "domain": "alt1.gmail-smtp-in.l.google.com"
//       },
//       {
//         "name": "gmail.com",
//         "ttl": 491,
//         "pref": 20,
//         "domain": "alt2.gmail-smtp-in.l.google.com"
//       },
//       {
//         "name": "gmail.com",
//         "ttl": 491,
//         "pref": 30,
//         "domain": "alt3.gmail-smtp-in.l.google.com"
//       },
//       {
//         "name": "gmail.com",
//         "ttl": 491,
//         "pref": 40,
//         "domain": "alt4.gmail-smtp-in.l.google.com"
//       }
//     ]
//   }
// }

// Use this online tool to generate parsing code from sample JSON: 
// Generate Parsing Code from JSON

i := 0;
count_i := CkJsonObject_SizeOfArray(json,'answer.mx');
while i < count_i do
  begin
    CkJsonObject_putI(json,i);
    name := CkJsonObject__stringOf(json,'answer.mx[i].name');
    ttl := CkJsonObject_IntOf(json,'answer.mx[i].ttl');
    pref := CkJsonObject_IntOf(json,'answer.mx[i].pref');
    domain := CkJsonObject__stringOf(json,'answer.mx[i].domain');
    i := i + 1;
  end;

CkDns_Dispose(dns);
CkJsonObject_Dispose(json);

end;