I am on a Windows server (IIS not Apache), WP 3.1 installed, Multisite enabled, but stuck with how to configure for aliased domains:
domain1.com (primary)
domain2.com (aliased)
domain3.com (aliased)
Aliased meaning the domain is pointing to the primary domain.
My IPS is using WebsitePanel.
When I attempt to Create a New Site in WordPress, entering domain2.com, I get "Missing or invalid site address."