How to mask subdomains redirect

[duskdawn]

Hi
When I created a sub domain in cpanel, sometimes it can automatically setup masked redirect, like this
cn.linkremoved.biz

but sometimes, it resulted in plain redirect without mask, like this
mwang.linkremoved.biz

Did I miss something here? Could anyone tell me how to make the second one like the first one?

Thank you and happy new year.