How to create the CNAME records for Outbound DKIM signing using GoDaddy DNS | Office 365 | Part 8#10 5/5 (1) 5 min read

In the current article, we provide step by step guideline, for the task of – creating the required two “DKIM CNAME records,” that we needed to publish.

This is a preliminary step that we must complete. Only after the required “DKIM CNAME” records were successfully created, we can continue to the last step, in which we enable that outbound DKIM signing for a specific domain name registered with Office 365.

Scenario and task description

The scenario

The domain for which we want to activate the “outbound DKIM signing” is – o365pilot.com

The prerequisite for enabling the outbound DKIM signing is – a creation of two CNAME records, that will be created in the DNS server who hosts the specified domain.

In our scenario, the 2 “DKIM CNAME” records, will include the following host’s names:

CNAME record 1#2

  • Host = selector1._domainkey
  • Points to => selector1-o365pilot-com._domainkey.o365info2.onmicrosoft.com
CNAME record 2#2

  • Host = selector2._domainkey
  • Points to => selector2-o365pilot-com._domainkey.o365info2.onmicrosoft.com
Note – in case that you need to get more information about this specific host’s names whom we use in our scenario, and the PowerShell command that we use for getting the required host names for a specific domain; you can read the article – Get the value of the DKIM record for a Domain, using PowerShell | Office 365 | Part 7#10.
.

The Task

Using our public DNS management interface for creating the required two CNAME record that will be used for DKIM outbound signing in Office 365 environment.

Creating the required two CNAME required for Outbound DKIM signing using GoDaddy DNS management interface.

In the next section, I will demonstrate how to create the two CNAME records, that will point to the Office 365 DKIM Selectors using the GoDaddy DNS management interface.

Regarding “other DNS management interfaces,” the major concepts of creating CNAME records are less or more the same on every DNS management interface, beside of some minor changes.

Creating DKIM CNAME records for Outbound DKIM signing – Office 365 - 01

In the Gooday DNS management interface

  • Select the DNS ZONE FILE tab
  • Select the option of – Add Record

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In our scenario, we would like to create a NEW CNAME record.

  • In the RECORD TYPE:* option box, click on the small arrow

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  • Select the option of – CNAME (Alias) record

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In our specific scenario, the CNAME record will include the following hosts names:

In the “upper section” named – HOST:, we will add the host name: selector1._domainkey

It’s important to understand that because this hostname is hosted “under” the domain name –  o365pilot.com , the FQDN (Fully qualified Hostname) will be – selector1._domainkey.o365pilot.com

In other words, don’t add the “full hostname” in the upper part, but only the “partial hostname” without the “Domain suffix part.”

The host name in the “upper part,” will be used for redirected requests to the dedicated Office 365 DKIM Selector record, that includes the Office 365 DKIM Public Key.

In the “bottom section” named – POINTS TO:, we will add the following host name:

selector1-o365pilot-com._domainkey.o365info2.onmicrosoft.com

Creating DKIM CNAME records for Outbound DKIM signing – Office 365 - 05

Before we continue, it’s important to me to briefly review the concept of the DNS CNAME record because, many times this concept can be a bit confusing.

The CNAME record serves as a “logical router” that accepts a request for “object A” and redirects the required to “object B.”
In our case, each DNS query for the “DKIM selector” that is represented by the host name – selector1._domainkey.o365pilot.com, will be redirected
to the Host name selector1-o365pilot-com._domainkey.o365info2.onmicrosoft.com

The flow logic of CNAME record When asking for Host X-the request will be redirected to host Y

Creating and configuring the second DKIM CNAME record

We will need to repeat this process for cratering an additional CNAME record, that will use for redirecting DKIM request to additional Office 365 host named – selector2

To add an additional record, we will click on the button – ADD ANOTHER

In the “upper section” named – HOST:, we will add the host name: selector2._domainkey

In the “bottom section” named – POINTS TO:, we will add the host name:

selector2-o365pilot-com._domainkey.o365info2.onmicrosoft.com

Creating DKIM CNAME records for Outbound DKIM signing – Office 365 - 07

  • Save the new CNAME records that added by selecting the menu – Save Changes.

Creating DKIM CNAME records for Outbound DKIM signing – Office 365 - 08

In the following screenshot, we can see the result; two new CNAME records created.

Creating DKIM CNAME records for Outbound DKIM signing – Office 365 - 09

The next step

It’s recommended to continue to read the next article, which describe the “next step,” in which we review the process of – verify if the DKIM CNAME records are successfully published and available for external clients.

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