I have recently planned to install an exchange server in branch office.
Craete new DAG and Install 2 DAG members and create new CAS Array for the databases of branch servers.
Please check this
Now what will happen if the branch office user access OWA from external network?
How this can be configured for branch users?
Example Main office is in US and and new branch office is in UK.
How UK users will access OWA from outside(internet)?