Cnames and "virtual name based hosting"

[fih]

Hello!

I have heard rumors that it would be illegeal and bad to use Cnames to point
out websites at webhotels using "virtual name based hosting".

Like this:

unixbox.domain.com. IN A 1.1.1.1

www.customer1.com. IN CNAME unixbox.domain.com.
www.customer2.com. IN CNAME unixbox.domain.com.
www.customer3.com. IN VNAME unixbox.domain.com.

WIth my knowledge this is good DNS management!

Any comments are apreciated and if you can refer to an RFC i apreciate it
even more!