4
Thank you both for the quick response!!
I have tried two approaches:
1. redirect as you suggested. I don't use cpanel, so I put the location in the index.php page. It works fine except it showed redirected URL after redirection.
2. I used iframe to put the long URL page into index.html of the subdomain page. This way, it only show the subdomain address, but then when I click something else in the page, since it is inside a frame, even it showed another page it still show the subdomain address :)
Compare them I think redirect is better.
But is any other options ?