Click on the below link to download document for installing Exchange 2010 SAN certificate from Internal Root CA.
Ø Creating New Exchange certificate using Exchange management console and generating CSR to internal Domain controller to get SAN Certificate
Ø Installing pre-requisites for CA Server.
Ø Installing the CA Server to get SAN certificate.
Ø Submitting the Exchange 2010 CSR to get SAN certificate.
Ø Installing SAN certificate to Exchange 2010 Trusted root.
Ø Complete the pending Exchange certificate using Exchange management console. (Importing Certificate)
Ø Enable exchange 2010 client services on SAN certificate.