Here you will find the presentation and a little video related to the speech I held at INTEROP in Mumbai Voice In The Cloud: The Hybrid Approach and the Online Future (Interop 2013 session) from Fabrizio Volpe
The changes in the Lync 2013 client autodiscover process (and also in the Lync 2010 client, as I will explain later) and the possibility to use mismatched domains between the SRV and Host (A) records open an interesting opportunity to downsize the required SAN names to a total of six (S I X).
Lync Online Hybrid Deployment with Split Domain
This scenario requires and on-premises deployment of Lync and an agreement with an Office 365 / Lync 2013 online multi-tenant.
This solution allows enabling our Lync users to Lync online or to Lync on-premises, leaving to the Lync administrator the capability to migrate them from one situation to the other one and vice-versa smoothly.