Added an additional front end server to my Lync 2010 Ent pool and learned a thing or two that I would like to share in case someone else needs this info.
Getting the first front end server with backend SQL was easy enough (there a lot of step by step webites you can reference for that), but I ran into a few questions when implementing an additional front end for redundancy that the web wasn't so forth coming with its information. The best link I found was http://lyncinsider.com/conferencing/how-to-add-new-servers-to-lync-20-tasks-every-lync-administrator-must-know/
. Of course, all of the documentation you see references using a hardware load balancer (HLB) but there is also the reference to using DNS load balancing as well.
What I seem to have determined was that the pool needs to be DNS load balanced and the webservices, harware load balanced. So for example, my Enterprise pool name is pool1.domain.com and my FE servers are lync1.domain.com and lync2.domain.com ;
so in DNS, I created two A records for pool1.domain.com (one for each IP address of my FE(s).
I also created a A record called lync.domain.com whose IP address is the VIP for the HLB. I re-ran Topology builder and changed the Internal web services from what I had (which was pool1.domain.com) to lync.domain.com. On my HLB, I have the appropriate services defined for Lync and they are tied to my two FE servers.
My external web services are set to the FQDN of my reverse proxy.
Lastly, be mindfull of using Interal CA for your certificates. I ran into an issue with my HLB in using a non-trusted CA and even though I had the company add the root CA into the trusted store on the appliance, I still had to use an option on the appliance to not "validate certificate".
Hope I could help.