www prefix not working for any domains

[hereintokyo]

I am running Plesk 10.3.1 on Media Temple, linux.

The www prefix does not work for any of my domains. If I go to http://example.com, I can see my site, but if I go to www.example.com, it goes to the default site for the IP address.

Ideally, I would like to use URL rewriting to redirect www.example.com to http://example.com

According to this article, www is enabled by default on 10.3.1

http://kb.parallels.com/en/9288

But it is definitely not working.

So far, I have tried:

Adding www CNAME records to the DNS zone files

Adding URL rewriting to htaccess or vhost.conf files

All of the support I have seen on this issue seems to refer to earlier versions of Plesk that included domain administration.

Any help would be appreciated.