I am setting up a web site for a client. She is using GoDaddy for domain registration, and a hosting company I have never used before. After setting up the nameservers on GoDaddy's side, the address foobar.com (for example) is correctly directing to the new site. However, the address www.foobar.com is redirecting to a 404 page on the hosting company's side.

I've been dealing with customer service on the hosting side, and they have told me various things including wait for DNS propagation (which has obviously happened since the 404 page is on their side), and to make sure that the nameservers on GoDaddy's side were entered in lower case instead of upper case (which I know doesn't matter since nameservers are case insensitive).

I think I'm getting the runaround from the hosting company, but the client had signed up with them before I came to the project, so if possible I'd like to resolve this issue with them before we start treating it as a loss.

Does anybody know what could cause foobar.com to resolve correctly but www.foobar.com to not resolve? How would I best be able to suggest a fix to this through the technical support channels of a hosting company?