setup default DNS server with only one record

[Chris Henderson]

I am trying to setup a default DNS server for one of my restricted
network segment so that no matter what people type in their browser,
they will be redirected to a single IP address or the hostname. The
zone file that I have setup is partially working - it resolves
<anything>.mydomain.com to a single IP address but doesn't resolve
<anything>.some-other-domain.com (eg. www.cnn.com) - it just gives up.
Here is my zone file. Any help would be highly appreciated. Thanks.

$TTL 1W
@               IN SOA          nms.mydomain.com.   hostmaster.mydomain.com. (
                                42              ; serial
                                2D              ; refresh
                                4H              ; retry
                                6W              ; expiry
                                1W )            ; minimum

@               ns              nms.mydomain.com.
*               A               192.168.25.25