How to configure a sub-domain?

[Ronan Lucio]

Hi All,

I have configured a sub-domain in a server, but I think I doing
something wrong.

I have cofigured the follow way:

The named.conf file of the main domain server has:

zone "domain.com" {
    type master;
    file "pri.domain.com";
};

zone "sub.domain.com"{
    type slave;
    file "sec.sub.domain.com";
    masters {
        192.168.1.1;
    };
};

So, the main domain will be always updated and any changes in
sub.domain zone file will be public at all.

But, it doesn´t seem working properly, if I ping www.sub.domain.com
from a external machine, it isn´t visible, just in main server.

What am I doing wrong?

Thank´s to all
Ronan