In Tools/Domain Mapping it is asking for a Custom Domain for the member.
My domain that runs WPMU is an add on domain at my host
which I tested in my browser after installing the domain mapping tool following the direction and it brought me back to the main blog site home page.
2. What exactly do I enter for "A" record in this case? And again what goes in Custom Domain field?
I am testing an actual website http://www.realweb site.com