I would like to find out how do i configure CRM Dynamics portal to enable external users to log into the portal without being members of the domain. Do i have to extend CRM to do it?.
If you want to login to CRM directly, I don't think its possible to do so without adding them to your domain.
If you want to give external users access to your CRM data, but not your CRM, you might want to look into Dynamics CRM Portals (formerly know as Adxstudio portals) https://www.microsoft.com/en-us/dynamics/crm-setup-and-administration/install-crm-portals.aspx