We are deploying ADFS on server 2012 R2. Microsoft recommends a minimum of 2 ADFS servers, and 2 servers running the web application proxy role in the DMZ.
My question is: We already have in place 2 Apache reverse proxy servers in the DMZ running mod_balancer. Besides loosing the ability to do pre-authentication. Is where any reason to use microsoft web application proxy servers vs apache? We do not have a hardware load-balancer.
In other words. What are the implications of using redundant Apache reverse_proxies (VRRP) + mod_reverse_balancer to load balance the ADFS farm vs. Windows Application Proxies using NLB and ADFS farm using NLB?