I've been interested since starting with Mojo in its ability to handle multiple sites with one installation, but to be honest, I can't understand the docs explaining how that can be done. Yeah, I get the "folder" scheme, but the "hostname" scheme, I just don't get it -- that stuff with "hosting headers", "bindings," etc -- obviously I have no access to anything like that. I had thought maybe I just needed to use subdomains to get that to work, but I dunno, that's not really what the docs would indicate, with all that "hosting headers" and "bindings" stuff. Maybe it's just the terminology that's messing with me; if I have a domain hosted at Mocha, then create a subdomain from that domain (which is also, of course, hosted at the same place that the domain is), isn't that the same thing? I really don't get it.
Your instincts are right on here. The "hostname" method can also use subdomains. So, if your domain name was andria.com, you could have sites at www.andria.com, books.andria.com, blogs.andria.com, etc. All you would need to do for this is make sure that your hosting company has entries in their published DNS for each of your subdomains, and in the mojoPortal Administration, Site Settings, Host Name Mapping tab, make sure that the appropriate subdomain is listed for each of your sites. That is how we are doing it, and it's super simple.
I'll take a look at the multiple sites via host name portion of that document and see if I can make it a bit easier to understand.