Hmmm sounds like someone needs a lesson in IT classes. You need an A record for sub-domains. CNAMEs are intended if you have multiple servers with different functions. server.domain.com would be the webserver, sql.domain.com would be the sql database, ftp.domain.com would be the ftp server, etc.... Also, you have to CONFIGURE the program to accept (exclusively, or not) just those connections. Example of that would be my server (no longer runs this way!): [www.]jbls.kiatos.tk redirects to my jbls stats page whereas both kiatos.tk and blog.kiatos.tk redirected to my websites, thereby leaving ftp.kiatos.tk was my ftp server (I no longer OWN kiatos.tk).
Basically, even though they were on the same computer, you could only connect to each one was properly configured. Ofc not one was allowed to accept connections from an alternate "server name." Its pretty much all done for security purposes. And actually, when you think about it, it makes sense that why my friend called the setup mini-cloud computing. =D