Make public for all AD users

I have setup an SharePoint 2013 Intranet site and would like to give "All General employees (AD users)" with public access on site collection. A few set of users (i.e. managers) those have some special permissions will be managed with sharepoint groups.<o:p></o:p>

How can I setup this?. Is this a setting in while creating web application?. <o:p></o:p>

Pl. help.  <o:p></o:p>

sam <o:p></o:p>

sam