Windows dns server primary zone question

hello,

I have read and know that you can host a windows primary dns zone on only one dns server and all the other copies of the same zone ( on any other dns servers) has to be secondary. But i see something different with what i do here in my test domains.

Can anyone help me where am i wrong or is there some changes that happened recently? OR Is it that i can host a primary zone in a single dns server in a domain and i can host on another DNS server provided it is on another domain ? 

Thanks


http://www.4shared.com/file/185932068/d0644c66/Doc1.html