Which Lync Server 2013 server role should you recommend deploying to each server?

Explanation/Reference:
Note:
* Edge Server enables your users to communicate and collaborate with users outside the organization’s firewalls. These external users can include the organization’s own users who are currently working offsite, users from federated partner organizations, and outside users who have been invited to join conferences hosted on your Lync Server deployment.
* A Director is a server running Lync Server 2013 that authenticates user requests, but does not home any user accounts. You optionally can deploy a Director in the following two scenarios:
/ If you enable access by external users by deploying Edge Servers, you should also deploy a Director. In this scenario, the Director authenticates the external users, and then passes their traffic on to internal servers. When a Director is used to authenticate external users, it relieves Front End pool servers from the overhead of performing authentication of these users. It also helps insulate internal Front End pools from malicious traffic such as denial-of-service attacks. If the network is flooded with invalid external traffic in such an attack, this traffic ends at the Director.
/ If you deploy multiple Front End pools at a central site, by adding a Director to that site you can streamline authentication requests and improve performance. In this scenario, all requests go first to the Director, which then routes them to the correct Front End pool.
Reference: Overview of the Director