> ... if you want a subdomain of ww.com...
and naturally understood "subdomain" to mean "subdomain".
Perhaps what you meant to write was
"... if you want a hostname in ww.com..."
ww.com is a nice 2nd level domain. A 3rd level domain zyx.ww.com would be pretty nice too, in which one could create several hostnames, such as blog.zyx.ww.com, hg.zyx.ww.com, etc.
Yes, if you delegated the DNS for the subdomain, it would not be as easy for you to see what hostnames are in that subdomain.
It's already a bit of a risk as it is (hence the 20 karma cap, I'm not too strict in looking at that if an account wasn't made 20 minutes ago), but I don't want to get burned.
I agree that the formal interpretation of 'subdomain' is one with delegation, but when someone says they put their usernames on 'subdomains' it is commonly understood to be a 3rd level host name, and not one with full delegation.
You could have surmised that from the bit that asks for 'the ip to go with it' and not for 'the ips of the name servers to go with it'.