We are creating a DR site at remote location (active/passive model). This will be a passive site (passive databases with stretched DAG) only to be used in case of disaster for complete site failover. I am wondering if we should go with shared/same namespace (mail.company.com) or separate/different namespace (dr.company.com) for DR site? It seems from Microsoft best practices, they advise separate namespace but no clear documentation and steps guide with it. How will failover affect the exchange services (outlook, owa, eas, outlook anyware, ActiveSync., autodiscover, cas array). Any advice/comments/experience are appreciated.