This question isn't really related to Azure Active Directory. Looks like a similar thread was created here though. https://www.reddit.com/r/sysadmin/comments/5vrzy6/exchange_azure_site_recovery/
Also, from the documentation:
"Exchange DAGs are the recommended solution for Exchange disaster recovery in an enterprise. Site Recovery recovery plans can include DAGs, to orchestrate DAG failover across sites."
https://learn.microsoft.com/en-us/azure/site-recovery/site-recovery-workload
I'm not an ASR expert though so you would be best off asking in the Azure Storage forums, which have not yet migrated to Q&A. (They'll be migrated in may though) https://social.msdn.microsoft.com/forums/azure/en-US/home?forum=windowsazuredata