We currently have two Exchange 2010 servers with roles separated. One local mailbox server without CAS in our building and a CAS with no mailboxes in a remote datacenter.
We plan to migrate to 2013 with two new servers hosting all roles on each and then shut down the 2010 servers. There will be one local and one in a datacenter for Exchange 2013 so that either server could be individually restarted without internal LAN users losing email access. (We do not want to open network access from the Internet to the onsite CAS). Is it practical to set it up this way?
How do we get the existing certificates (mail, autodiscover, and the local host name etc.) moved from the 2010 to the 2013 to the new servers when I assume they both must be running side by side for at least a short time while mailboxes are moved form 2010 to 2013? Will we need to buy new SSL certificates since the local host machine names for the Exchange server 2013 servers will be new and there will be more than one CAS?