I have a domain (let's call it foo.com) that's not hosted on Dreamhost -- I run both the DNS and the web server for it.
What I want to do is to host http://bar.foo.com/ on Dreamhost, without moving the rest of foo.com over. I also want to retain control over the DNS of foo.com -- I was thinking I might make bar.foo.com a CNAME to apache2-ogle.thunderkittens.dreamhost.com, or delegate the entire bar.foo.com tree to Dreamhost's nameservers, or something like that.
What I'm running into is, I can't even add "bar.foo.com" as a domain, in Dreamhost. When I'm under "Manage Domains" and I click "Add new domain/subdomain", fill in the details, and press "Fully host this domain", it gives me an error: "You can't add that domain: you don't have permission to add to foo.com". (well, the error includes my actual domain, not foo.com, but...).
What is it checking, to determine that I don't have permission? Would it help if I added some DNS records to foo.com first, and then tried again later? If so, what DNS records should I add -- the CNAME idea, or the delegation idea?
I found http://wiki.dreamhost.com/Using_a_Foreign_Nameserver but it didn't seem to be making any clear suggestions on what to do.