Is Dreamhost hosted by Rackspace?

Is Dreamhost hosted by Rackspace?
Why is Dreamhost not hosted by themself?

C:\Documents and Settings\Administrator>nslookup

Non-authoritative answer:

IP Lookup Result for
IP Address:
Organization: Rackspace Cloud Servers
ISP: Rackspace Hosting
City: San Antonio
Country: United States
State: Texas
Postal Code: 78218
Timezone: America/Chicago
Local Time: 22.08.2014 00:52:51

Our web site is hosted with a CDN that has some points of presence within Rackspace’s network.

I just had a comment deleted from this thread because I made a humourous statement about why DreamHost might not use their own hosting.

While your humor is appreciated, what you’d written was worded as a factual (and incorrect) statement about our service, which could confuse visitors. Keep in mind that many of the users viewing this forum may have found it through a search engine, and hence may not realize some of the context.