If you want to enroll your devices with Microsoft Intune and you have your own DNS then this is the setting you want to put into it:

dns

Remember: If you have Split Brain DNS or a second DNS in the DMZ, put the same CNAME alias there aswel.

FDQN is always “enterpriseenrollment.yourdomain.com”

Make sure if you have some advance proxy setup or routing that they are on the same subnet.