Exchange - Enable DAG encryption and compression

By default DAG is configured to use compression and encryption only for intersubnet replication replication.

[PS] C:\>Get-DatabaseAvailabilityGroup | fl Name,NetworkEncryption,NetworkCompression

Name               : DAG2010
NetworkEncryption  : InterSubnetOnly
NetworkCompression : InterSubnetOnly

Name               : DAG2013
NetworkEncryption  : InterSubnetOnly
NetworkCompression : InterSubnetOnly

It is a good practice to enable them on all DAG networks and for both replication and seeding by executing the following Powershell:

[PS] C:\>Get-DatabaseAvailabilityGroup DAG2010 | Set-DatabaseAvailabilityGroup -NetworkEncryption Enabled -NetworkCompression Enabled

[PS] C:\>Get-DatabaseAvailabilityGroup DAG2013 | Set-DatabaseAvailabilityGroup -NetworkEncryption Enabled -NetworkCompression Enabled

(Each DAG version must be configured executing the powershell in the Exchange of the same version)

[PS] C:\>Get-DatabaseAvailabilityGroup | fl Name,NetworkEncryption,NetworkCompression

Name               : DAG2010
NetworkEncryption  : Enabled
NetworkCompression : Enabled

Name               : DAG2013
NetworkEncryption  : Enabled
NetworkCompression : Enabled

For technicals details:
https://technet.microsoft.com/en-us/library/dd298065%28v=exchg.150%29.aspx