"www" question


I've got a client who can not view their website within their internal network when the "www" is typed into the URL. The rest of the world has no problems.

Any ideas on how I can advise them?
I'd audit their BIND configuration and use the +trace option in dig to see what their resolvers are doing differently from everyone else.
I had a client with a similar problem except they could not view the site without the www. Turns out their local Windows server domain was 'domain.com', the same as their website. They just use the www to get to the website.