unable to view the external hosted website without www.

HI all,
my company have almost 60 computer with 2003 enterprize as AD. on the same server we have DNS and i add all entries which require to access the external website bcoz we are using the same name for active directory domain. the problem is this site is up and working fine from outside of my office without www if i didn’t add www in anyclient of my network its not working i checked in DNS for www entry with CNAME the both are working fine and correct.. is there anybody who will help me in this regard their help will be highly appriciated