The Catch-all option forwards any non-existing hostname to a specific location.
Now-DNSs Update API is based around many of the existing APIs for other DDNS services available today.
The DNS customization tool enables customers with advanced technical domain knowledge to make and manage unlimited changes to a Domain Name Zone File.
When you purchase a domain name like mydomain.com, that is a host name, but it is considered the default host name for the domain because it has no host segment.
With any domain name you can actually setup any number of host names like foo.mydomain.com, and cheeseburger.are all valid host names you could setup for your domain.
It is actually very easy to setup additional root level web sites in IIS on your dev machine and use the hosts file to map fake host names for testing.
Its helpful to understand what the difference is between a host name and a domain name.