Ok, that configuration looks fine.
However, it looks like your using IP based virtual hosting which means that it looks at the IP rather than server name. So, any name in your DNS that resolves to that IP will be able to access the home page.
I haven't setup named virtual hosting in awhile but, you might want to check the docs on the apache site. If I remember correctly they have a pretty good section on setting up virtual hosts.
You can use the search and look for virtual host.