An Active Directory site is stretched if it is spread across multiple physical sites. Exchange setup may vary from organization to organization. Some Exchange organization are single site , some are multi site and some times single sites is spread across multiple AD site. In this series of two posts, I will show you how to recover an Exchange 2013 Data Availability Group in a stretched AD site.
Exchange 2013 DAG recovery in a stretched AD site – Part 1
Exchange 2013 DAG recovery in a stretched AD site – Part 2
I hope this article gives you a clear picture of understanding and recovering the DAG in the stretched AD site scenario 
Shameless Null Neutrality
Good day to you,
i have two question, regarding your post in exchange DAG 2013 failover you did not show the full command for alternate file share witness switchover to primary site. kindly show us please.
what about AD, AD on 2nd site will serve user on 1st site ? i mean when there is no PDC role on 2nd site ?
thanks