The recommended way of installing the Exchange 2013 Edge Transport server is on a workgroup member (stand-alone server) in the DMZ. However, it is not uncommon that customers are implementing an Active Directory domain in their DMZ for management purposes.
In my previous blog post I explained how to install the first Front-End server in a Front-End pool. To extend the functionality we are now going to install a Lync 2013 Edge server. Using the Edge server users can logon to the Lync environment externally, and you can setup a federation with other companies to communicate with users in these companies as well.