how to config virtual hosting

I created a local dns and setup foo.com as my domain.

Now, I want to setup mrtg.foo.com I created virtual hosting in my apache

Here is my apache config

ServerName 127.0.0.1
NameVirtualHost mrtg.foo.com

<VirtualHost mrtg.foo.com>
ServerAdmin root@localhost
DocumentRoot /var/www/html/mrtg
ServerName mrtg.foo.com
ErrorLog logs/foo-error_log
CustomLog logs/foo_com-access_log common
</VirtualHost>

Here is my zone file in my dns

foo.com. IN A 10.0.1.14
www IN A 10.0.1.14
mrtg IN A 10.0.1.14

The problem is the site mrtg.foo.com and foo.com display the same. Is there a problem in my apache and dns config file?

Have you tried adding a VIP (virtual IP) and binding the virtual host to said VIP?

What distro are you using?