How to generate DKIM correctly?

Question

linux

There are 5 domains on which you want to install DKIM and DMARK
1 DNS server
2. Server (hosting)
The task is to sign mail sending.
Question 1 there is a site mydefile.ru hosting sends mail from hosting.mywildorchid.ru

eceived: from mxfront1h.mail.yandex.net ([127.0.0.1])
  by mxfront1h.mail.yandex.net with LMTP id E4nHijgB
  for <[email protected]>; Mon, 14 Dec 2015 11:44:04 +0300
Received: from wildorchid.ru (wildorchid.ru [95.213.143.209])
  by mxfront1h.mail.yandex.net (nwsmtp/Yandex) with ESMTP id nayxVv2pvc-i3Dei9v9;
  Mon, 14 Dec 2015 11:44:03 +0300
Return-Path: [email protected]
X-Yandex-Front: mxfront1h.mail.yandex.net
X-Yandex-TimeMark: 1450082643
Authentication-Results: mxfront1h.mail.yandex.net; spf=pass (mxfront1h.mail.yandex.net: domain of wildorchid.ru designates 95.213.143.209 as permitted sender) [email protected]; dkim=fail [email protected]
X-Yandex-Spam: 1
Received: by hosting.wildorchid.ru (Postfix, from userid 600)
  id 51CF122408AB; Mon, 14 Dec 2015 11:44:03 +0300 (MSK)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=mydefile.ru;
  s=default; t=1450082643;
  bh=X82F/8qtLtvxoQ1qDRKiHtuPrjsn4TPRPUy8y3i6r7I=;
  h=To:Subject:Date:From;
  b=Sz1Vl3jgmN3phXQTPx/9ny7r47UxIxM9K7nz+igBBjB5OS8Q/OnTCkN8eUGTP8iFD
   E5xawT3R0xAO6g0BZX/EIbLxPllKa2hHTBALQo4GM4l1ErVvHYq1zVM8CIrUWQJGC/
   InTy8nOznGsEwEveh91gU6tn6gVWSViNtdJtqSus=
To: =?koi8-r?B?c2hhbWJsZXI4MUB5YW5kZXgucnU=?= <[email protected]>
Subject: =?koi8-r?B?RMXGySrMxTog0M/E1NfF0tbExc7JxSDQz8TQydPLyQ==?=
X-PHP-Originating-Script: 600:common.php
Date: Mon, 14 Dec 15 11:44:03 +0300
From: =?koi8-r?B?RMXGySrMxQ==?= <[email protected]>
Content-type: text/html; charset="koi8-r"
Content-Transfer-Encoding: base64

Naturally from already from [email protected]
Question whom should I add in the future?
mydefile.ru or a real sender?

Answer 1

d=mydefile.ru is the domain whose TXT record is requested when looking for a DKIM key