Note - It takes couple of hours to activate the custom domain. Contact support@ngage.ai for any issues activating custom domain.
To set up the DNS redirect for the root domain (like user going to https://mydomain.com) the CNAME entry in the DNS setting will be CNAME with @ (for root) and the target will be your sub-domain within https://ngage.ai. See the screenshot below.
The entry for root domain
To setup the DNS redirect for the sub-domain (https://subdomain.mydomain.com) add the CNAME entry for the sub-domain as follows and mapping to your sub-domain in https://ngage.ai