I have a domain (my.com) containing 5 subdomains (www.my.com, app1.my.com, app2.my.com, app3.my.com, app4.my.com).
The 4 apps are hosted on a Windows/Apache 2.4 server with a single IP using virtual hosts, while www.my.com is hosted on a second server with a separate IP and may move to a managed hosting service in the future.
I have to secure all of the above subdomains with SSL certificates from Geotrust.
What I need is to:
Choose the appropriate type of certificates that can work in the above configuration (5 subdomains in 2 servers)
Minimize the number of certificates required (for cost and maintenance reasons)
Maintain a generally acceptable degree of security
So, how many certificates should I order and of which type?