Is it possible to use an ANAME (A) dns record instead of CNAME with Custom URL?


Description

There is a requirement to have emails sent from the instance use the same domain as the custom URL.

eg


ServiceNow Documentation states that a CNAME is required in dns as a pre-requisite for a CustomURL.

Whilst it is simple to change the FROM address via the email account in the instance, an MX record is required in dns to allow replies to reach the instance.

RFC1034 states that “If a CNAME RR is present at a node, no other data should be present; this ensures that the data for a canonical name and its aliases cannot be different.” Thus the MX record cannot be added.

On researching this online there are several suggestions to use an ANAME dns record instead of CNAME as an ANAME record can be used with an MX record.

When Defining a CustomURL on the instance it is required to have the CNAME record already registered in dns else an error is received and the CustomURL cannot be activated.

After the CustomURL is configured we have changed the CNAME record to ANAME and defined the MX record.

The question is whether this is supported or not?

Cause

Resolution

Using ANAME is not an option for the above reasons.

An alternative is to use an external POP\IMAP email server within the mycompany.com domain, instead of the ServiceNow provided POP email account.

Replies to emails from the instance would be delivered to this external email server and then retrieved by the instance.