July 2010 Question of the Month
Does Exchange 2010’s DAG support encryption? If so, what types?
ANSWER:
Yes. Encryption types are based on host OS support. BUT, DAGs only use encryption across different subnets & no encryption is used during the initial seed.
http://www.windowsitpro.com/article/exchange-server-2010/Database-Availability-Group-Compression-Encryption.aspx