I'm in the process of just figuring out the process of setting up a gateway server (Using Apache reverse proxy with SSL) to host multiple web sites. I just wanted to confirm which server would require the certificate.
So, for example, if my gateway server was reverse proxying Example1.com (10.0.0.1), Example2.com (10.0.l0.2) and Example3.com (10.0.0.3), would I require:
a) A certificate for each server and it's domain, plus one for the gateway server
b) Just one certificate for the gateway server, with the 3 domains
c) A certificate for each web hosting server