Just came across this really interesting and useful article on using secondary pools for Lync resilience and the best way of getting clients to pick up the secondary pool in the event of failure.

http://blogs.technet.com/b/dodeitte/archive/2010/12/26/another-reason-to-include-a-director-in-your-lync-server-2010-deployment.aspx

Happy reading.

NeilC