In a previous post I did a basic overview of syncing customers between two AX instances using SQL MDS. I thought I’d got back through the setup of this so you can see how the infrastructure pieces connect.
You can find documentation here on TechNet for the setup of AX MDM.
PS. Just an add to this. In the video I covered some of the security settings. You might want to have a look at this blog post for additional notes on security setup as it relates to MDS setup with AX.