It still amazes me how many server admins fail to properly configure their web servers and dns so that foo.com works just as well as www.foo.com
On the other hand, there is a whole group of people who think that the ‘www’ is absolutely required, and even if you tell them to go to bar.foo.com, they will go to www.bar.foo.com, so make sure you set that up as well. It’s easy in Apache, just add a ServerAlias like so:
ServerName bar.foo.com ServerAlias www.bar.foo.com
A simple fix, and hopefully it will help prevent having to explain to people that you don’t need to type the ‘www’ part, just let them do it, it’s easier to fix things on the server than in people’s brains.
(And if you can’t make this fix on your server yourself, ask whoever maintains your server to make it for you.)